Personalized security document and method of personalizing a security document

Abstract

A personalized security document (10) includes a first personalized image (4, 4a) laser engraved in at least one layer of laser-engravable material (2, 12) from a first side (S1) of the security document (10), and a second personalized image (5, 5a) laser engraved in the at least one layer of laser-engravable material (2, 12) from a second side (S2) of the security document (10). Both the first personalized image and the second personalized image exhibit a color-change effect when viewed in reflection. In some cases, the two personalized images are engraved in two different layers of laser-engravable material (2, 12).

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 is used. In some applications, a laser engraved image is considered vital, as the image features are obtained inside a polycarbonate substrate rather than on the surface of the substrate. A laser engraved feature in a polycarbonate substrate may include a black and white (in particular, grayscale) image, a color image, or other special features.

[0003] There are also other approaches for providing security features for such identification documents or other security documents. For example, WO 2015 / 083099 A1 discloses a security structure comprising a layer containing a binder and goniochromatic metal particles inside the binder.

[0004] US 2021 / 0053382 A1 discloses a method of manufacturing an identification document comprising a first visual marking and a second visual marking engraved using different laser powers.

[0005] 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

[0006] According to one aspect of the present disclosure, a personalized 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 the substrate along the thickness direction. The security feature includes at least one layer of laser-engravable material embedded in the substrate. The at least one layer of laser-engravable material includes at least a first material that exhibits a color-change effect when viewed in reflection at different observation angles. The security feature further includes a first personalized image laser engraved in the at least one layer of laser-engravable material from the first side. The first personalized image exhibits a color-change effect when viewed in reflection from the first side at different observation angles, preferably, under white light. The security feature also includes a second personalized image laser engraved in the at least one layer of laser-engravable material from the second side. The second personalized image exhibits a color-change effect when viewed in reflection from the second side at different observation angles, preferably, under white light.

[0007] In another aspect of the present disclosure, a method of personalizing a security document includes the steps of providing a personalizable security document including 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 the substrate along the thickness direction, the security feature including at least one layer of laser-engravable material embedded in the substrate, the at least one layer of laser-engravable material including at least a first material that exhibits a color-change effect when viewed in reflection at different observation angles, preferably, under white light, laser engraving a first personalized image in the at least one layer of laser-engravable material from the first side such that the first personalized image exhibits a color-change effect when viewed in reflection from the first side at different observation angles, preferably, under white light, and laser engraving a second personalized image in the at least one layer of laser-engravable material from the second side such that the second personalized image exhibits a color-change effect when viewed in reflection from the second side at different observation angles, preferably, under white light.

[0008] In a further aspect, the present disclosure relates to a personalizable security document having 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 the substrate along the thickness direction. The security feature includes a first layer of laser-engravable material embedded in the substrate and configured to have a first personalized image laser engraved in the same from the first side, the first layer of laser-engravable material including at least a first material that exhibits a color-change effect when viewed in reflection at different observation angles, preferably, under white light, and a second layer of laser-engravable material configured to have a second personalized image laser engraved in the same from the second side, the second layer of laser-engravable material overlapping the first layer of laser-engravable material at least in part when viewed along the thickness direction and including at least a second material that exhibits a color-change effect when viewed in reflection at different observation angles, preferably, under white light.

[0009] Other features and aspects of the present disclosure will be apparent from the following description and the accompanying drawings.Brief Description of the Drawings

[0010] Fig. 1 shows a plan view of an exemplary personalizable security document in accordance with the present disclosure; Fig. 2 is a schematic cross-sectional view of a personalized security document in accordance with the present disclosure; Fig. 3 is a plan view of an exemplary personalized security document in accordance with the present disclosure when viewed from a first side under a first observation angle; Fig. 4 is another plan view of the exemplary personalized security document in accordance with the present disclosure when viewed from the first side under a second observation angle; Fig. 5 is a plan view of the exemplary personalized security document in accordance with the present disclosure when viewed from a second side under a first observation angle; Fig. 6 is a plan view of the exemplary personalized security document in accordance with the present disclosure when viewed from the second side under a second observation angle; Fig. 7 is a plan view of an exemplary personalized security document in accordance with the present disclosure when viewed from the first side against white light; Fig. 8 is a plan view of the exemplary personalized security document in accordance with the present disclosure when viewed from the second side against white light; Fig. 9 is a schematic cross-sectional view of another personalized security document in accordance with the present disclosure; and Fig. 10 is a flow diagram illustrating a method of personalizing a security document in accordance with the present disclosure. Detailed Description

[0011] 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.

[0012] The present disclosure is based at least in part on the realization that personalized features such as secondary portraits play an important role in security documents, as they add a security element to such documents. Sometimes, such secondary portraits are combined with other features such as embossings, holograms, color-shifting inks, thermochromic inks, etc. in order to make a document more secure. The present disclosure is based on the realization that the security of such documents can be increased further by providing personalized images that have a color-shifting effect on both sides of the security document, in particular, in a window that extends through the security document.

[0013] It has been realized that, in particular in cases where the material in which the images are engraved from both sides is the same, the images can be engraved using a single laser, in particular, a single laser wavelength, by varying other laser parameters in a manner that is essentially the same for both images. This facilitates manufacturing the security document, in particular, personalizing the same by providing the two personalized images on both sides of the security document.

[0014] The present disclosure is also based on the realization that security can be increased even further by providing an additional feature, in particular, a watermark that overlaps the two personalized images formed on both sides of the security document. In this manner, the watermark can be viewed when the security document is viewed in transmission, i.e., against white light. In such a state, one or both of the personalized images may not be recognizable, because the layer of material to which the images are engraved has a certain opacity, such that the engraved image features cannot be recognized against the background provided by the material layer when the document is viewed against white light.

[0015] Here, it has been realized that, in order to be able to laser engrave the images from both sides of the security document, the watermark may be provided such that it does not overlap the region of the material layer into which one of the two images is to be engraved, in order to facilitate engraving the image. Additionally, in such a case, both the watermark and the laser engraved image on one side of the document can be viewed in reflection, e.g., under white light, from the corresponding side of the security document, adding an additional layer of security, because the engraved image has to be aligned with the watermark when engraving the same.

[0016] It has also been realized that it may be advantageous to provide two layers of laser-engravable material on opposite sides of the security document, such that each personalized image is engraved in its own layer of material from the respective side. This may further facilitate the personalization of the security document. It may also allow for different combinations of materials of the laser-engravable layers, which may exhibit different color-change effects. In such cases, different laser wavelengths or other laser parameters may be required to laser engrave the respective images. This may pose an additional difficulty when unauthorized parties try to replicate or forge the security document.

[0017] The present disclosure may also be based at least in part on the realization that it is advantageous to provide the laser-engravable materials on a background layer, for example, an artwork or the like of the security document, that is printed onto a substrate layer of a substrate forming the security document. This may further facilitate manufacturing of the security document, and the printed background can contribute to the effect of the engraved images not being visible in transmission.

[0018] Fig. 1 shows a plan view of an exemplary security document 10 in accordance with the present disclosure. As shown in Fig. 1, security document 10 includes a substrate 1, for example, a polycarbonate or polyvinyl chloride (PVC) substrate having a substantially rectangular shape. In some embodiments, as shown in Fig. 3, security document 10 may be a personalized security document, i.e., include an image 11 (for example, a photograph or the like) of a person to which the document belongs. Image 11 may be formed in an image region provided on a first side S1 of substrate 1 in a known manner.

[0019] In addition, as shown in Fig. 1, document 10 includes a security feature 3 formed in substrate 1, for example, in the shape of a rectangular window in which one or more security features can be provided. For example, as shown in Fig. 3, security feature 3 may include a first laser engraved image 4, which may correspond to image 11 (for example, may be an inverse or negative of image 11), in a layer of laser-engravable material 2 of security feature 3. This will be described in more detail in the following.

[0020] It will be appreciated that, after manufacturing, security document 10 may be a personalizable security document. In other words, image 11 my not yet be present, and layer of laser-engravable material 2 may be unmodified, such that security document 10 is not personalized (see Fig. 1). Generally, such personalization will be carried out by the respective issuers of the security documents, for example, passports, identification cards, driver's licenses or the like, as will also be described in more detail below.

[0021] Fig. 2 shows a schematic cross-sectional view of personalized security document 10 in accordance with an exemplary embodiment. As shown in Fig. 2, personalized security document 10 comprises 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 is formed by stacking a plurality of substrate layers 31, 32, 33, 34, 35, for example, polycarbonate or PVC layers, and combining them in an appropriate manner, for example, by lamination processes or the like. This is known to the skilled person, such that a detailed description will be omitted herein.

[0022] 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 the uppermost substrate layer 31 to the bottom layer 35 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.

[0023] As shown in Fig. 2, layer of laser-engravable material 2 is embedded in substrate 1. In accordance with the present disclosure, layer of laser-engravable material 2 includes at least a first material that exhibits a color-change effect when viewed at different observation angles, for example, under white light. In some embodiments, layer of laser-engravable material 2 is provided as an ink that is applied onto substrate layer 32 in an appropriate manner, for example, by screen printing or offset printing.

[0024] Generally, laser-engravable inks having a color-change effect are known, for example, from WO 2015 / 083099 A1. As described in said document, such a laser-engravable ink is essentially formed from metallic particles that provide a color-change or goniochromatic effect. In some embodiments of the present disclosure, such goniochromatic particles are used in combination with an organic material, for example, an organic layer formed on top of the layer including the goniochromatic particles, or a coating of the metallic particles, or a mixture of the goniochromatic particles with additional (for example, organic) pigments to obtain an ink that has a desired first color when viewed at a first observation angle. Preferably, a ratio between the organic material and the metallic particles is between 1:2 and 2:1, for example, around 1:1. This configuration results in that, when security document 10 is viewed from first side S1 under white light at the first observation angle, for example, substantially 90 degrees, layer of laser-engravable material 2 is observed as having the first color.

[0025] The security feature 3 includes a first personalized image 4, 4a laser engraved in layer of laser-engravable material 2 from first side S1 in such a manner that first personalized image 4, 4a exhibits a color-change effect when viewed in reflection, for example, under white light from first side S1 at different observation angles. This is illustrated in Figs. 3 and 4, which show a plan view of personalized security document 10 when viewed from first side S1 under different observation angles. Under a first observation angle shown in Fig. 3, first personalized image 4 has a first appearance, and under second observation angle, which is shown in Fig. 4, first personalized image 4a has a different appearance, i.e., is perceived as a different image. This results in the color-change effect of the present disclosure for the first personalized image.

[0026] In accordance with the present disclosure, security feature 3 further includes a second personalized image 5, 5a laser engraved in layer of laser-engravable material 2 from second side S2, as shown in Fig. 2. As shown in Figs. 5 and 6, second personalized image 5, 5a also has a color-change effect when viewed under white light from second side S2 at different observation angles, which are shown in Figs. 5 and 6, respectively.

[0027] In some embodiments, for example, first personalized image 4, 4a may be a secondary portrait of the holder of security document 10, i.e., an image that resembles image 11, for example, is a negative image of the same. Additionally, in some embodiments, a second personalized image 5, 5a may include personalized information such as, for example, a date of birth of the holder of security document 10, a different view of the portrait that corresponds to image 11, a mixture of a positive image and a negative image, or other encoded information. Additionally, as will be appreciated by the skilled person, security document 10 also may include further personalized information 13 provided in a known manner outside of security feature 3 on second side S2 of security document 10, for example, personalized data such as a date of birth, place of birth, address, etc. of the holder of security document 10.

[0028] As previously mentioned, the first material of layer of laser-engravable layer 2 includes goniochromatic particles that result in the desired color-change effect. Moreover, an additional color layer, or additional pigments may be provided in order to provide layer of laser-engravable layer 2 and personalized images 4, 4a, 5, 5a with a desired color or colors. For example, initially, layer of laser-engravable layer 2 may have a first color (for example, blue). As previously described, the presence of the goniochromatic particles inside the first material results in that, when substrate 1 is tilted, the color of layer of laser-engravable layer 2 changes (for example, from blue to green). Upon personalization of document 10, depending on the laser power, for example, the goniochromatic effect of the particles inside the first material, and / or the transparency of the layer of laser-engravable layer 2 may be altered. For example, different portions of layer of laser-engravable layer 2 may exhibit different amounts of color-change. Additionally, a further color change may result due to the presence of additional pigments inside layer of laser-engravable layer 2. For example, when viewed at the first observation angle, the initial color of layer of laser-engravable layer 2 may gradually change with increasing laser power. In this manner, personalized images 4, 4a, 5, 5a that may correspond to image 11 and exhibit a color-change when viewed under white light can be engraved in layer of laser-engravable layer 2.

[0029] In the exemplary embodiment shown in Fig. 2, layer of laser-engravable material 2 is configured as a single layer of laser-engravable material 2, and first and second personalized images 4, 4a, 5, 5a are laser engraved in opposite sides (i.e., opposite surfaces) of the single layer of laser-engravable material 2 using laser light L. Here, it will be appreciated that, due to the presence of the single layer of laser-engravable material 2, the same laser light L may be used to engrave first personalized image 4, 4a and second personalized image 5, 5a, by varying laser parameters of the same. Exemplary laser parameters are repetition rate, laser speed, laser power, focus depth, etc. Exemplary values of the laser parameters are 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. As the engraving of images by varying laser parameters is well-known, no further description will be provided herein.

[0030] In some embodiments, single layer of laser-engravable material 2 has a height h in thickness direction d of between 8 µm and 15 µm, preferably between 10 µm and 12 µm. In particular, it may be advantageous to choose a height h in the above range in order to allow engraving of the respective personalized images in the opposite surfaces of layer of laser-engravable material 2 without an interference between the same. Additionally, height h may be chosen such that layer of laser-engravable material 2 remains opaque after forming first and second personalized images 4, 4a, 5, 5a. As will be described in the following, this results in that, when security document 10 is viewed against white light, image features of first personalized image 4, 4a and second personalized image 5, 5a may vanish against the opaque background provided by layer of laser-engravable material 2, even if the portions of the substrate layers overlapping layer of laser-engravable material 2 are transparent.

[0031] Although in the previous embodiment layer of laser-engravable material 2 is configured as a single layer, the present disclosure is not limited to such a configuration. Fig. 9 shows another embodiment in accordance with the present disclosure, in which layer of laser-engravable material 2 includes a first layer of laser-engravable material 2 embedded in substrate 1 and having first personalized image 4, 4a laser engraved in the same from first side S1, and a second layer of laser-engravable material 12 embedded in substrate 1 and having a second personalized image 5, 5a laser engraved in the same from second side S2, wherein the second layer of laser-engravable material 2 overlaps the first layer of laser-engravable material 2 at least in part when viewed along thickness direction d. Also in this configuration, first personalized image 4, 4a and second personalized image 5, 5a can be laser engraved from first side S1 and second side S2, respectively, using laser light L in an appropriate manner. However, the configuration may provide additional flexibility, both with respect to the materials and the arrangement of the respective layers of laser-engravable material 2, 12. Moreover, the interplay between the two layers makes it more difficult to tamper with security document 10, because any attempt to manipulate one layer may also affect or even destroy the other layer.

[0032] In some embodiments, first layer of laser-engravable material 2 and second layer of laser-engravable material 12 both include the first material that exhibits a color-change effect. In other words, a composition of first layer of laser-engravable material 2 and second layer of laser-engravable material 12 may be essentially the same. In some embodiments, first layer of laser-engravable material 2 and second layer of laser-engravable material 12 may include different materials exhibiting the color-change effect. For example, different types of metallic particles may be included in the respective layers, or different additional pigments may be provided to result in different colors of the respective layers. The ratio between the organic material and the metallic particles may also be different for both layers.

[0033] The height h of the individual layers of laser-engravable material 2 may be different from the height h in case only a single layer of laser-engravable material is present, or may be the same. A distance between the layers of laser-engravable material 2, 12 along thickness direction d may be between 0 µm and 800 µm, preferably between 500 µm and 700 µm.

[0034] As shown in Fig. 9, in some embodiments, at least one of first layer of laser-engravable material 2 and second layer of laser-engravable material 12 is formed on a printed background layer 8 which is printed, for example, onto substrate layers 32 and 34 on which the respective layers of laser-engravable material 2, 12 are provided.

[0035] As shown in Figs. 2 and 9, in some embodiments, security feature 3 further comprises a watermark 7 formed in substrate 1 and overlapping at least part of the at least one layer of laser-engravable material 2, 12 when viewed in the thickness direction d. Such a watermark is commonly known, so that a detailed description will be omitted. However, generally, watermark 7 is a pattern that is printed onto a first substrate layer, for example, substrate layer 33 or 34 in a known manner, for example, by screen printing, offset printing, flexography, and the like. As shown in Figs. 7 and 8, watermark 7 is visible when security document 10 is viewed from at least one of first side S1 and second side S2 against white light (in the present example, from both sides). As previously mentioned, in some embodiments, first personalized image 4, 4a is not visible when security document 10 is viewed against white light from first side S1, and / or second personalized image 5, 5a is not visible when security document 10 is viewed against white light from second side S2.

[0036] In some embodiments, as shown in Fig. 2, watermark 7 is provided such that it is visible when security document 10 is viewed from second side S2 in reflection, for example, under white light. This is possible, because watermark 7 is provided in a substrate layer that is below the substrate layer on which layer of laser-engravable material 2 is provided, and the portions of the remaining substrate layers (i.e., substrate layers 34 and 35) on second side S2 are transparent forming the window of security feature 3. As such, watermark 7 may be visible together with second personalized image 5, 5a when security document 10 is viewed from second side S2 under white light. Here, as schematically shown in Figs. 7 and 8, it may be advantageous to provide watermark 7 in such a manner that it does not overlap the region of layer of laser-engravable material 2 in which second personalized image 5, 5a is engraved, in order to not interfere with the engraving. In other embodiments, however, watermark 7 may be at least partially transparent at the wavelength of laser light L that used to engrave second personalized image 5, 5a, and watermark 7 may overlap the region of layer of laser-engravable material 2 into which second personalized image 5, 5a is engraved. Depending on the properties of watermark 7, this may change the color-change effect in the part of second personalized image 5, 5a that overlaps watermark 7.

[0037] In some embodiments, as shown in Fig. 9, watermark 7 may only be visible when security document 10 is viewed against white light, i.e., in transmission. This is because, in case first and second layers of laser-engravable material 2, 12 are provided, watermark 7 may be arranged on a substrate layer that is sandwiched between the substrate layers on which the respective layers of laser-engravable material 2, 12 are provided.

[0038] Although the above embodiments were described with respect to a personalized security document 10, i.e., a security document after personalization, the present disclosure also relates to a personalizable security document 10, i.e., a security document prior to personalization, comprising substrate 1 having first side S1 and second side S2 opposite to first side S1 in thickness direction d of substrate 1, and security feature 3 formed in substrate 1 extending through substrate 1 along thickness direction d, wherein security feature 3 includes first layer of laser-engravable material 2 embedded in substrate 1 and configured to have first personalized image 4, 4a laser engraved in the same from first side S1, and second layer of laser-engravable material 12 configured to have second personalized image 5, 5a laser engraved in the same from second side S2. First layer of laser-engravable material 2 includes at least a first material that exhibits a color-change effect when viewed under white light in different observation angles, and second layer of laser-engravable material 12 overlaps first layer of laser-engravable material 2 at least in part when viewed along thickness direction d and includes at least a second material that exhibits a color-change effect when viewed under white light at different observation angles.

[0039] Here, it will be appreciated, that, in some cases, first material and second material may be the same, i.e., first layer of laser-engravable material 2 and second layer of laser-engravable material 12 may include the same material that exhibits a color-change effect. In particular, in some embodiments, the composition of first layer of laser-engravable material 2 and second layer of laser-engravable material 12 may be the same. However, in other embodiments, the compositions of first layer of laser-engravable material 2 and second layer of laser-engravable material 12 may be different.

[0040] It will be appropriated that the above description with respect to personalized security document 10 concerning first and second layers of laser-engravable material 2, 12 also applies in case security document 10 is a personalizable security document, i.e., prior to personalization. This applies, in particular, to the respective heights of the layers of laser-engravable material, the arrangement of the same with respect to watermark 7, if present, etc.Industrial applicability

[0041] With the above-described configurations, a security document such as an ID card, a driver's license or the like having a security feature which includes a combination of different features can be obtained. In particular, a personalized security document 10 can be obtained, which includes a first personalized image having a color-change effect on a first side, and a second personalized image having a color-change effect on a second side of security document 10. As two images have to be laser engraved as part of security feature 3, which requires knowledge of the laser parameters to be used in order to successfully engrave the images without destroying either the layers of laser-engravable material or other features such as watermark 7, it becomes very difficult to forge or tamper with personalized security document 10.

[0042] An exemplary method of personalizing security document 10 will be described in the following with reference to Fig. 10. In a first step 110, personalized security document 10 including substrate 1 having a first side S1 and a second side S2 opposite to first side S1 in a thickness direction d of the substrate 1, and a security feature 3 formed in substrate 1 and extending through the substrate along thickness direction d, is provided. Here security feature 3 includes at least one layer of laser-engravable material 2 embedded in substrate 1, the at least one layer of laser-engravable material 2 including at least a first material that exhibits a color-change effect when viewed under white light at different observation angles.

[0043] In a second step 120, a first personalized image 4, 4a is laser engraved in the at least one layer of laser-engravable material 2 from first side S1 such that first personalized image 4, 4a exhibits a color-change effect when viewed under white light from first side S1 at different observation angles. This is achieved by appropriately varying laser parameters of the laser light that is used to engrave first personalized image 4, 4a, such that, in particular, the first material of layer of laser-engravable material 2 keeps its color-change properties.

[0044] In a subsequent step 130, a second personalized image 5, 5a is laser engraved in the at least one layer of laser-engravable material 2 from the second side S2 such that second personalized image 5, 5a exhibits a color-change effect when viewed under white light from the second side S2 at different observation angles.

[0045] The above applies to both the case in which a single layer of laser-engravable material 2 is provided, and the case in which two layers of laser-engravable material 2, 12 are provided. In the same manner, as described above, in case two layers of laser-engravable material 2, 12 are provided, they may have the same configuration, or may have different configurations. Accordingly, the laser parameters that are used for laser engraving first personalized image 4, 4a and second personalized image 5, 5a may be the same or may be different. Exemplary laser parameters that are used to engrave first personalized image 4, 4a and second personalized image 5, 5a are 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.

[0046] 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.

[0047] 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.

[0048] 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.

Examples

Embodiment Construction

[0011]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.

[0012]The present disclosure is based at least in part on the realization that personalized features such as secondary portraits play an important role in security documents, as they add a security element to such documents. Sometimes, such secondary portraits are combined with other features such as embossings, holograms, color-shifting inks, thermochromic inks, etc. in order to make a document more secure. The pre...

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 is used. In some applications, a laser engraved image is considered vital, as the image features are obtained inside a polycarbonate substrate rather than on the surface of the substrate. A laser engraved feature in a polycarbonate substrate may include a black and white (in particular, grayscale) image, a color image, or other special features.

[0003] There are also other approaches for providing security features for such identification documents or other security documents. For example, WO 2015 / 083099 A1 discloses a security structure comprising a layer containing a binder and goniochromatic metal particles inside the binder.

[0004] US 2021 / 0053382 A1 discloses a method of manufacturing an identification document comprising a first visual marking and a second visual marking engraved using different laser powers.

[0005] 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

[0006] According to one aspect of the present disclosure, a personalized 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 the substrate along the thickness direction. The security feature includes at least one layer of laser-engravable material embedded in the substrate. The at least one layer of laser-engravable material includes at least a first material that exhibits a color-change effect when viewed in reflection at different observation angles. The security feature further includes a first personalized image laser engraved in the at least one layer of laser-engravable material from the first side. The first personalized image exhibits a color-change effect when viewed in reflection from the first side at different observation angles, preferably, under white light. The security feature also includes a second personalized image laser engraved in the at least one layer of laser-engravable material from the second side. The second personalized image exhibits a color-change effect when viewed in reflection from the second side at different observation angles, preferably, under white light.

[0007] In another aspect of the present disclosure, a method of personalizing a security document includes the steps of providing a personalizable security document including 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 the substrate along the thickness direction, the security feature including at least one layer of laser-engravable material embedded in the substrate, the at least one layer of laser-engravable material including at least a first material that exhibits a color-change effect when viewed in reflection at different observation angles, preferably, under white light, laser engraving a first personalized image in the at least one layer of laser-engravable material from the first side such that the first personalized image exhibits a color-change effect when viewed in reflection from the first side at different observation angles, preferably, under white light, and laser engraving a second personalized image in the at least one layer of laser-engravable material from the second side such that the second personalized image exhibits a color-change effect when viewed in reflection from the second side at different observation angles, preferably, under white light.

[0008] In a further aspect, the present disclosure relates to a personalizable security document having 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 the substrate along the thickness direction. The security feature includes a first layer of laser-engravable material embedded in the substrate and configured to have a first personalized image laser engraved in the same from the first side, the first layer of laser-engravable material including at least a first material that exhibits a color-change effect when viewed in reflection at different observation angles, preferably, under white light, and a second layer of laser-engravable material configured to have a second personalized image laser engraved in the same from the second side, the second layer of laser-engravable material overlapping the first layer of laser-engravable material at least in part when viewed along the thickness direction and including at least a second material that exhibits a color-change effect when viewed in reflection at different observation angles, preferably, under white light.

[0009] Other features and aspects of the present disclosure will be apparent from the following description and the accompanying drawings.Brief Description of the Drawings

[0010] Fig. 1 shows a plan view of an exemplary personalizable security document in accordance with the present disclosure; Fig. 2 is a schematic cross-sectional view of a personalized security document in accordance with the present disclosure; Fig. 3 is a plan view of an exemplary personalized security document in accordance with the present disclosure when viewed from a first side under a first observation angle; Fig. 4 is another plan view of the exemplary personalized security document in accordance with the present disclosure when viewed from the first side under a second observation angle; Fig. 5 is a plan view of the exemplary personalized security document in accordance with the present disclosure when viewed from a second side under a first observation angle; Fig. 6 is a plan view of the exemplary personalized security document in accordance with the present disclosure when viewed from the second side under a second observation angle; Fig. 7 is a plan view of an exemplary personalized security document in accordance with the present disclosure when viewed from the first side against white light; Fig. 8 is a plan view of the exemplary personalized security document in accordance with the present disclosure when viewed from the second side against white light; Fig. 9 is a schematic cross-sectional view of another personalized security document in accordance with the present disclosure; and Fig. 10 is a flow diagram illustrating a method of personalizing a security document in accordance with the present disclosure. Detailed Description

[0011] 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.

[0012] The present disclosure is based at least in part on the realization that personalized features such as secondary portraits play an important role in security documents, as they add a security element to such documents. Sometimes, such secondary portraits are combined with other features such as embossings, holograms, color-shifting inks, thermochromic inks, etc. in order to make a document more secure. The present disclosure is based on the realization that the security of such documents can be increased further by providing personalized images that have a color-shifting effect on both sides of the security document, in particular, in a window that extends through the security document.

[0013] It has been realized that, in particular in cases where the material in which the images are engraved from both sides is the same, the images can be engraved using a single laser, in particular, a single laser wavelength, by varying other laser parameters in a manner that is essentially the same for both images. This facilitates manufacturing the security document, in particular, personalizing the same by providing the two personalized images on both sides of the security document.

[0014] The present disclosure is also based on the realization that security can be increased even further by providing an additional feature, in particular, a watermark that overlaps the two personalized images formed on both sides of the security document. In this manner, the watermark can be viewed when the security document is viewed in transmission, i.e., against white light. In such a state, one or both of the personalized images may not be recognizable, because the layer of material to which the images are engraved has a certain opacity, such that the engraved image features cannot be recognized against the background provided by the material layer when the document is viewed against white light.

[0015] Here, it has been realized that, in order to be able to laser engrave the images from both sides of the security document, the watermark may be provided such that it does not overlap the region of the material layer into which one of the two images is to be engraved, in order to facilitate engraving the image. Additionally, in such a case, both the watermark and the laser engraved image on one side of the document can be viewed in reflection, e.g., under white light, from the corresponding side of the security document, adding an additional layer of security, because the engraved image has to be aligned with the watermark when engraving the same.

[0016] It has also been realized that it may be advantageous to provide two layers of laser-engravable material on opposite sides of the security document, such that each personalized image is engraved in its own layer of material from the respective side. This may further facilitate the personalization of the security document. It may also allow for different combinations of materials of the laser-engravable layers, which may exhibit different color-change effects. In such cases, different laser wavelengths or other laser parameters may be required to laser engrave the respective images. This may pose an additional difficulty when unauthorized parties try to replicate or forge the security document.

[0017] The present disclosure may also be based at least in part on the realization that it is advantageous to provide the laser-engravable materials on a background layer, for example, an artwork or the like of the security document, that is printed onto a substrate layer of a substrate forming the security document. This may further facilitate manufacturing of the security document, and the printed background can contribute to the effect of the engraved images not being visible in transmission.

[0018] Fig. 1 shows a plan view of an exemplary security document 10 in accordance with the present disclosure. As shown in Fig. 1, security document 10 includes a substrate 1, for example, a polycarbonate or polyvinyl chloride (PVC) substrate having a substantially rectangular shape. In some embodiments, as shown in Fig. 3, security document 10 may be a personalized security document, i.e., include an image 11 (for example, a photograph or the like) of a person to which the document belongs. Image 11 may be formed in an image region provided on a first side S1 of substrate 1 in a known manner.

[0019] In addition, as shown in Fig. 1, document 10 includes a security feature 3 formed in substrate 1, for example, in the shape of a rectangular window in which one or more security features can be provided. For example, as shown in Fig. 3, security feature 3 may include a first laser engraved image 4, which may correspond to image 11 (for example, may be an inverse or negative of image 11), in a layer of laser-engravable material 2 of security feature 3. This will be described in more detail in the following.

[0020] It will be appreciated that, after manufacturing, security document 10 may be a personalizable security document. In other words, image 11 my not yet be present, and layer of laser-engravable material 2 may be unmodified, such that security document 10 is not personalized (see Fig. 1). Generally, such personalization will be carried out by the respective issuers of the security documents, for example, passports, identification cards, driver's licenses or the like, as will also be described in more detail below.

[0021] Fig. 2 shows a schematic cross-sectional view of personalized security document 10 in accordance with an exemplary embodiment. As shown in Fig. 2, personalized security document 10 comprises 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 is formed by stacking a plurality of substrate layers 31, 32, 33, 34, 35, for example, polycarbonate or PVC layers, and combining them in an appropriate manner, for example, by lamination processes or the like. This is known to the skilled person, such that a detailed description will be omitted herein.

[0022] 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 the uppermost substrate layer 31 to the bottom layer 35 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.

[0023] As shown in Fig. 2, layer of laser-engravable material 2 is embedded in substrate 1. In accordance with the present disclosure, layer of laser-engravable material 2 includes at least a first material that exhibits a color-change effect when viewed at different observation angles, for example, under white light. In some embodiments, layer of laser-engravable material 2 is provided as an ink that is applied onto substrate layer 32 in an appropriate manner, for example, by screen printing or offset printing.

[0024] Generally, laser-engravable inks having a color-change effect are known, for example, from WO 2015 / 083099 A1. As described in said document, such a laser-engravable ink is essentially formed from metallic particles that provide a color-change or goniochromatic effect. In some embodiments of the present disclosure, such goniochromatic particles are used in combination with an organic material, for example, an organic layer formed on top of the layer including the goniochromatic particles, or a coating of the metallic particles, or a mixture of the goniochromatic particles with additional (for example, organic) pigments to obtain an ink that has a desired first color when viewed at a first observation angle. Preferably, a ratio between the organic material and the metallic particles is between 1:2 and 2:1, for example, around 1:1. This configuration results in that, when security document 10 is viewed from first side S1 under white light at the first observation angle, for example, substantially 90 degrees, layer of laser-engravable material 2 is observed as having the first color.

[0025] The security feature 3 includes a first personalized image 4, 4a laser engraved in layer of laser-engravable material 2 from first side S1 in such a manner that first personalized image 4, 4a exhibits a color-change effect when viewed in reflection, for example, under white light from first side S1 at different observation angles. This is illustrated in Figs. 3 and 4, which show a plan view of personalized security document 10 when viewed from first side S1 under different observation angles. Under a first observation angle shown in Fig. 3, first personalized image 4 has a first appearance, and under second observation angle, which is shown in Fig. 4, first personalized image 4a has a different appearance, i.e., is perceived as a different image. This results in the color-change effect of the present disclosure for the first personalized image.

[0026] In accordance with the present disclosure, security feature 3 further includes a second personalized image 5, 5a laser engraved in layer of laser-engravable material 2 from second side S2, as shown in Fig. 2. As shown in Figs. 5 and 6, second personalized image 5, 5a also has a color-change effect when viewed under white light from second side S2 at different observation angles, which are shown in Figs. 5 and 6, respectively.

[0027] In some embodiments, for example, first personalized image 4, 4a may be a secondary portrait of the holder of security document 10, i.e., an image that resembles image 11, for example, is a negative image of the same. Additionally, in some embodiments, a second personalized image 5, 5a may include personalized information such as, for example, a date of birth of the holder of security document 10, a different view of the portrait that corresponds to image 11, a mixture of a positive image and a negative image, or other encoded information. Additionally, as will be appreciated by the skilled person, security document 10 also may include further personalized information 13 provided in a known manner outside of security feature 3 on second side S2 of security document 10, for example, personalized data such as a date of birth, place of birth, address, etc. of the holder of security document 10.

[0028] As previously mentioned, the first material of layer of laser-engravable layer 2 includes goniochromatic particles that result in the desired color-change effect. Moreover, an additional color layer, or additional pigments may be provided in order to provide layer of laser-engravable layer 2 and personalized images 4, 4a, 5, 5a with a desired color or colors. For example, initially, layer of laser-engravable layer 2 may have a first color (for example, blue). As previously described, the presence of the goniochromatic particles inside the first material results in that, when substrate 1 is tilted, the color of layer of laser-engravable layer 2 changes (for example, from blue to green). Upon personalization of document 10, depending on the laser power, for example, the goniochromatic effect of the particles inside the first material, and / or the transparency of the layer of laser-engravable layer 2 may be altered. For example, different portions of layer of laser-engravable layer 2 may exhibit different amounts of color-change. Additionally, a further color change may result due to the presence of additional pigments inside layer of laser-engravable layer 2. For example, when viewed at the first observation angle, the initial color of layer of laser-engravable layer 2 may gradually change with increasing laser power. In this manner, personalized images 4, 4a, 5, 5a that may correspond to image 11 and exhibit a color-change when viewed under white light can be engraved in layer of laser-engravable layer 2.

[0029] In the exemplary embodiment shown in Fig. 2, layer of laser-engravable material 2 is configured as a single layer of laser-engravable material 2, and first and second personalized images 4, 4a, 5, 5a are laser engraved in opposite sides (i.e., opposite surfaces) of the single layer of laser-engravable material 2 using laser light L. Here, it will be appreciated that, due to the presence of the single layer of laser-engravable material 2, the same laser light L may be used to engrave first personalized image 4, 4a and second personalized image 5, 5a, by varying laser parameters of the same. Exemplary laser parameters are repetition rate, laser speed, laser power, focus depth, etc. Exemplary values of the laser parameters are 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. As the engraving of images by varying laser parameters is well-known, no further description will be provided herein.

[0030] In some embodiments, single layer of laser-engravable material 2 has a height h in thickness direction d of between 8 µm and 15 µm, preferably between 10 µm and 12 µm. In particular, it may be advantageous to choose a height h in the above range in order to allow engraving of the respective personalized images in the opposite surfaces of layer of laser-engravable material 2 without an interference between the same. Additionally, height h may be chosen such that layer of laser-engravable material 2 remains opaque after forming first and second personalized images 4, 4a, 5, 5a. As will be described in the following, this results in that, when security document 10 is viewed against white light, image features of first personalized image 4, 4a and second personalized image 5, 5a may vanish against the opaque background provided by layer of laser-engravable material 2, even if the portions of the substrate layers overlapping layer of laser-engravable material 2 are transparent.

[0031] Although in the previous embodiment layer of laser-engravable material 2 is configured as a single layer, the present disclosure is not limited to such a configuration. Fig. 9 shows another embodiment in accordance with the present disclosure, in which layer of laser-engravable material 2 includes a first layer of laser-engravable material 2 embedded in substrate 1 and having first personalized image 4, 4a laser engraved in the same from first side S1, and a second layer of laser-engravable material 12 embedded in substrate 1 and having a second personalized image 5, 5a laser engraved in the same from second side S2, wherein the second layer of laser-engravable material 2 overlaps the first layer of laser-engravable material 2 at least in part when viewed along thickness direction d. Also in this configuration, first personalized image 4, 4a and second personalized image 5, 5a can be laser engraved from first side S1 and second side S2, respectively, using laser light L in an appropriate manner. However, the configuration may provide additional flexibility, both with respect to the materials and the arrangement of the respective layers of laser-engravable material 2, 12. Moreover, the interplay between the two layers makes it more difficult to tamper with security document 10, because any attempt to manipulate one layer may also affect or even destroy the other layer.

[0032] In some embodiments, first layer of laser-engravable material 2 and second layer of laser-engravable material 12 both include the first material that exhibits a color-change effect. In other words, a composition of first layer of laser-engravable material 2 and second layer of laser-engravable material 12 may be essentially the same. In some embodiments, first layer of laser-engravable material 2 and second layer of laser-engravable material 12 may include different materials exhibiting the color-change effect. For example, different types of metallic particles may be included in the respective layers, or different additional pigments may be provided to result in different colors of the respective layers. The ratio between the organic material and the metallic particles may also be different for both layers.

[0033] The height h of the individual layers of laser-engravable material 2 may be different from the height h in case only a single layer of laser-engravable material is present, or may be the same. A distance between the layers of laser-engravable material 2, 12 along thickness direction d may be between 0 µm and 800 µm, preferably between 500 µm and 700 µm.

[0034] As shown in Fig. 9, in some embodiments, at least one of first layer of laser-engravable material 2 and second layer of laser-engravable material 12 is formed on a printed background layer 8 which is printed, for example, onto substrate layers 32 and 34 on which the respective layers of laser-engravable material 2, 12 are provided.

[0035] As shown in Figs. 2 and 9, in some embodiments, security feature 3 further comprises a watermark 7 formed in substrate 1 and overlapping at least part of the at least one layer of laser-engravable material 2, 12 when viewed in the thickness direction d. Such a watermark is commonly known, so that a detailed description will be omitted. However, generally, watermark 7 is a pattern that is printed onto a first substrate layer, for example, substrate layer 33 or 34 in a known manner, for example, by screen printing, offset printing, flexography, and the like. As shown in Figs. 7 and 8, watermark 7 is visible when security document 10 is viewed from at least one of first side S1 and second side S2 against white light (in the present example, from both sides). As previously mentioned, in some embodiments, first personalized image 4, 4a is not visible when security document 10 is viewed against white light from first side S1, and / or second personalized image 5, 5a is not visible when security document 10 is viewed against white light from second side S2.

[0036] In some embodiments, as shown in Fig. 2, watermark 7 is provided such that it is visible when security document 10 is viewed from second side S2 in reflection, for example, under white light. This is possible, because watermark 7 is provided in a substrate layer that is below the substrate layer on which layer of laser-engravable material 2 is provided, and the portions of the remaining substrate layers (i.e., substrate layers 34 and 35) on second side S2 are transparent forming the window of security feature 3. As such, watermark 7 may be visible together with second personalized image 5, 5a when security document 10 is viewed from second side S2 under white light. Here, as schematically shown in Figs. 7 and 8, it may be advantageous to provide watermark 7 in such a manner that it does not overlap the region of layer of laser-engravable material 2 in which second personalized image 5, 5a is engraved, in order to not interfere with the engraving. In other embodiments, however, watermark 7 may be at least partially transparent at the wavelength of laser light L that used to engrave second personalized image 5, 5a, and watermark 7 may overlap the region of layer of laser-engravable material 2 into which second personalized image 5, 5a is engraved. Depending on the properties of watermark 7, this may change the color-change effect in the part of second personalized image 5, 5a that overlaps watermark 7.

[0037] In some embodiments, as shown in Fig. 9, watermark 7 may only be visible when security document 10 is viewed against white light, i.e., in transmission. This is because, in case first and second layers of laser-engravable material 2, 12 are provided, watermark 7 may be arranged on a substrate layer that is sandwiched between the substrate layers on which the respective layers of laser-engravable material 2, 12 are provided.

[0038] Although the above embodiments were described with respect to a personalized security document 10, i.e., a security document after personalization, the present disclosure also relates to a personalizable security document 10, i.e., a security document prior to personalization, comprising substrate 1 having first side S1 and second side S2 opposite to first side S1 in thickness direction d of substrate 1, and security feature 3 formed in substrate 1 extending through substrate 1 along thickness direction d, wherein security feature 3 includes first layer of laser-engravable material 2 embedded in substrate 1 and configured to have first personalized image 4, 4a laser engraved in the same from first side S1, and second layer of laser-engravable material 12 configured to have second personalized image 5, 5a laser engraved in the same from second side S2. First layer of laser-engravable material 2 includes at least a first material that exhibits a color-change effect when viewed under white light in different observation angles, and second layer of laser-engravable material 12 overlaps first layer of laser-engravable material 2 at least in part when viewed along thickness direction d and includes at least a second material that exhibits a color-change effect when viewed under white light at different observation angles.

[0039] Here, it will be appreciated, that, in some cases, first material and second material may be the same, i.e., first layer of laser-engravable material 2 and second layer of laser-engravable material 12 may include the same material that exhibits a color-change effect. In particular, in some embodiments, the composition of first layer of laser-engravable material 2 and second layer of laser-engravable material 12 may be the same. However, in other embodiments, the compositions of first layer of laser-engravable material 2 and second layer of laser-engravable material 12 may be different.

[0040] It will be appropriated that the above description with respect to personalized security document 10 concerning first and second layers of laser-engravable material 2, 12 also applies in case security document 10 is a personalizable security document, i.e., prior to personalization. This applies, in particular, to the respective heights of the layers of laser-engravable material, the arrangement of the same with respect to watermark 7, if present, etc.Industrial applicability

[0041] With the above-described configurations, a security document such as an ID card, a driver's license or the like having a security feature which includes a combination of different features can be obtained. In particular, a personalized security document 10 can be obtained, which includes a first personalized image having a color-change effect on a first side, and a second personalized image having a color-change effect on a second side of security document 10. As two images have to be laser engraved as part of security feature 3, which requires knowledge of the laser parameters to be used in order to successfully engrave the images without destroying either the layers of laser-engravable material or other features such as watermark 7, it becomes very difficult to forge or tamper with personalized security document 10.

[0042] An exemplary method of personalizing security document 10 will be described in the following with reference to Fig. 10. In a first step 110, personalized security document 10 including substrate 1 having a first side S1 and a second side S2 opposite to first side S1 in a thickness direction d of the substrate 1, and a security feature 3 formed in substrate 1 and extending through the substrate along thickness direction d, is provided. Here security feature 3 includes at least one layer of laser-engravable material 2 embedded in substrate 1, the at least one layer of laser-engravable material 2 including at least a first material that exhibits a color-change effect when viewed under white light at different observation angles.

[0043] In a second step 120, a first personalized image 4, 4a is laser engraved in the at least one layer of laser-engravable material 2 from first side S1 such that first personalized image 4, 4a exhibits a color-change effect when viewed under white light from first side S1 at different observation angles. This is achieved by appropriately varying laser parameters of the laser light that is used to engrave first personalized image 4, 4a, such that, in particular, the first material of layer of laser-engravable material 2 keeps its color-change properties.

[0044] In a subsequent step 130, a second personalized image 5, 5a is laser engraved in the at least one layer of laser-engravable material 2 from the second side S2 such that second personalized image 5, 5a exhibits a color-change effect when viewed under white light from the second side S2 at different observation angles.

[0045] The above applies to both the case in which a single layer of laser-engravable material 2 is provided, and the case in which two layers of laser-engravable material 2, 12 are provided. In the same manner, as described above, in case two layers of laser-engravable material 2, 12 are provided, they may have the same configuration, or may have different configurations. Accordingly, the laser parameters that are used for laser engraving first personalized image 4, 4a and second personalized image 5, 5a may be the same or may be different. Exemplary laser parameters that are used to engrave first personalized image 4, 4a and second personalized image 5, 5a are 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.

[0046] 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.

[0047] 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.

[0048] 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.

Examples

Embodiment Construction

[0011]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.

[0012]The present disclosure is based at least in part on the realization that personalized features such as secondary portraits play an important role in security documents, as they add a security element to such documents. Sometimes, such secondary portraits are combined with other features such as embossings, holograms, color-shifting inks, thermochromic inks, etc. in order to make a document more secure. The pre...

Claims

1. A personalized 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 the substrate along the thickness direction (d), wherein the security feature (3) includes: - at least one layer of laser-engravable material (2, 12) embedded in the substrate (1), the at least one layer of laser-engravable material (2, 12) including at least a first material that exhibits a color-change effect when viewed in reflection at different observation angles; - a first personalized image (4, 4a) laser engraved in the at least one layer of laser-engravable material (2, 12) from the first side (S1), the first personalized image exhibiting a color-change effect when viewed in reflection from the first side (S1) at different observation angles; and - a second personalized image (5, 5a) laser engraved in the at least one layer of laser-engravable material (2, 12) from the second side (S2), the second personalized image exhibiting a color-change effect when viewed in reflection from the second side (S2) at different observation angles.

2. The security document of claim 1, wherein the at least one layer of laser-engravable material (2, 12) is a single layer of laser-engravable material (2), and the first and second personalized images (4, 4a, 5, 5a) are laser engraved in opposite sides of the single layer of laser-engravable material (2).

3. The security document of claim 2, wherein the single layer of laser-engravable material (2) has a height (h) in the thickness direction (d) of between 8 µm and 15 µm, preferably between 10 µm and 12 µm.

4. The security document of claim 1, wherein the at least one layer of laser-engravable material (2, 12) includes a first layer of laser-engravable material (2) embedded in the substrate (1) and having the first personalized image (4, 4a) laser engraved in the same from the first side (S1), and a second layer of laser-engravable material (12) embedded in the substrate (1) and having the second personalized image (5, 5a) laser engraved in the same from the second side (S2), the second layer of laser-engravable material (12) overlapping the first layer of laser-engravable material (2) at least in part when viewed along the thickness direction (d).

5. The security document of claim 4, wherein the first layer of laser-engravable material (2) and the second layer of laser-engravable material (12) both include the first material that exhibits the color-change effect.

6. The security document of claim 4, wherein the first layer of laser-engravable material (2) and the second layer of laser-engravable material (12) include different materials that exhibit the color-change effect.

7. The security document of any one of claims 4 to 6, wherein at least one of the first layer of laser-engravable material (2) and the second layer of laser-engravable material (12) is formed on a printed background layer (8).

8. The security document of any one of claims 1 to 7, wherein the at least one layer of laser-engravable material (2, 12) includes a mixture of a metallic material and an organic material, preferably an organic layer formed on top of or below the metallic material, preferably with a ratio between 1:2 and 2:1, in particular, around 1:1.

9. The security document of claim 8, wherein the metallic material includes a plurality of metallic particles, preferably aluminum and / or silver particles, optionally covered by one or more metal or metal oxide layers.

10. The security document of any one of claims 1 to 9, wherein the first personalized image (4, 4a) is not visible when the security document (10) is viewed in transmission from the first side (S1), and / or the second personalized image (5, 5a) is not visible when the security document (10) is viewed in transmission from the second side (S2).

11. The security document of any one of claims 1 to 10, further comprising a watermark (7) formed in the substrate (1) and overlapping at least part of the at least one layer of laser-engravable material (2, 12) when viewed in the thickness direction (d), the watermark (7) being visible when the security document (10) is viewed from at least one of the first side (S1) and the second side (S2) in transmission.

12. The security document of claim 11, wherein the watermark (7) is visible when the security document (10) is viewed from the second side (S2) in reflection.

13. The security document of any one of claims 1 to 12, wherein the substrate (1) includes a plurality of substrate layers (31, 32, 33, 34, 35), and the at least one layer of laser-engravable material (2, 12) is formed on one or more of the plurality of substrate layers (31, 32, 33, 34, 35), preferably by screen printing or offset printing.

14. A method of personalizing a security document (10), comprising: - providing a personalizable security document (10) including 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 the substrate along the thickness direction (d), the security feature (3) including at least one layer of laser-engravable material (2) embedded in the substrate (1), the at least one layer of laser-engravable material (2) including at least a first material that exhibits a color-change effect when viewed in reflection at different observation angles; - laser engraving a first personalized image (4, 4a) in the at least one layer of laser-engravable material (2) from the first side (S1) such that the first personalized image exhibits a color-change effect when viewed in reflection from the first side (S1) at different observation angles; and - laser engraving a second personalized image (5, 5a) in the at least one layer of laser-engravable material (2) from the second side (S2) such that the second personalized image exhibits a color-change effect when viewed in reflection from the second side (S2) at different observation angles.

15. 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 the substrate along the thickness direction (d), wherein the security feature (3) includes: - a first layer of laser-engravable material (2) embedded in the substrate (1) and configured to have a first personalized image (4, 4a) laser engraved in the same from the first side (S1), the first layer of laser-engravable material (2) including at least a first material that exhibits a color-change effect when viewed in reflection at different observation angles; and - a second layer of laser-engravable material (12) configured to have a second personalized image (5, 5a) laser engraved in the same from the second side (S2), the second layer of laser-engravable material (12) overlapping the first layer of laser-engravable material (2) at least in part when viewed along the thickness direction (d) and including at least a second material that exhibits a color-change effect when viewed in reflection at different observation angles.

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