Patent Description:
It relates more particularly to security features to authenticate a security document.

It relates more specifically to a security document comprising a body including a cavity extending in at least a part of a thickness of the body from one side of the body, and in which a window is embedded.

Nowadays identity documents are to be checked against counterfeiting and falsification in a fast and easy way, either manually or visually or automatically, i.e. by means of external devices.

It is known from document <CIT> an optically variable security element for securing valuable article. This article comprises an optically variable ink layer with specific pigments and a thermochromic ink layer.

A way of facilitating authentication of a security document is to incorporate a transparent and/or translucent window in a design of such a security document, which allows the usage of a "z-direction", i.e. a direction along a thickness of the window, to enhance the security level.

A goal of the present invention is to provide a security document in which the window limits risks of reproduction or falsification, and which provides an easy way to inspect the authenticity of the security document.

Accordingly, the invention provides a security document comprising a body, the body comprising at least one side and a cavity extending in at least a part of a thickness of the body from the side, and the body comprising a window embedded in the cavity, the window comprising at least an OVM part and a chromic material part, at least a portion of the OVM part being superimposed with at least a portion of the chromic material part, wherein the OVM part is a material which shows colour shifting effects depending on a colour of a background on which it is placed, the window comprises two layers of transparent part between which the chromic material part is positioned, and wherein the window comprises a laser sensitive part forming a back layer of the window, both transparent part layers surrounding the chromic material part being positioned between the OVM part layer and the laser sensitive part, the window comprising an additional pattern engraved in the laser sensitive part, at least a portion of the chromic material part is superimposed with at least a portion of the additional pattern.

Thus, security level of such a window can be drastically improved, whilst giving enhanced visual appearance and design identity to an inspector and a user or document providing authority, owing to a careful design of the window.

Such a window permits to take advantage of a depth, i.e. thickness, of the document (i.e. z-axis or z-direction).

The window can extend over only a part of the thickness of the body, or cross the entire thickness.

Such a window is further advantageously combined with other security features using a surface of the body.

For example, it can be combined with at least another security feature inside the bulk of the body, either above and/or below the OVM part, or even the window. For example, such another security feature can be a security artwork on one transparent layer.

The OVM part here designates a part of the window, which comprises an OVM.

An OVM is an optically variable material, i.e. a material which shows colour shifting effects depending on a colour of a background on which it is placed.

Thus, the OVM part is of a first colour when on a white background, and of a second colour, different from the first colour, when on a black background.

Here, "colour" includes any hue of colour, including colourless, as well as transparency or translucency.

Besides, a "white" background here means a background which is white or of any bright colour, while a "black" background here means a background which is black or of any dark colour.

In addition, an OVM is often UV fluorescent.

Document <CIT> describes for example such an optically variable material.

Such a material has appeared to be very interesting for securing and/or authenticating a product in order to fight against counterfeits or production of forgeries.

In an example, the optically variable material comprises a given concentration of an active substance comprising one or more fluorescent compound (s), particularly of the family of <NUM>,<NUM>-difluoro-<NUM>-bora-3a, 4a-diaza- s-indacenes or from the difluoroborane p-diketonate family (BF2bdks).

For example, the OVM part comprising the optically variable material also comprises a polymer in which the OVM is incorporated.

For example, the OVM part forms a layer of the window.

A chromic material part here designates a part of the window, which comprises a material the colour of which changes from a first colour to a second colour, which is different from the first one, under an external stimulus, which can be chemical or physical.

For example, without exposure, the chromic material part is of the first colour, and when the chromic material part is subjected to an exposure, it is of the second colour.

Such changes are often reversible, which means that the change of colour can be repeated and reproduced.

Here, the changes of colour are preferably reversible.

According to an example embodiment, the colour change of the chromic material occurs gradually in time, typically in the order of seconds or minutes. Then, the chromic material often is time dependent in its colours changes.

According to one example embodiment, the chromic material part comprises at least one of a thermochromic material or a photochromic material.

A thermochromic material is a chromic material which is sensitive to temperature, while a photochromic material is a material which is sensitive to light; the light being for example general visible light (i.e. a light comprising at least one wavelength comprised between about <NUM> and <NUM>), or UV light (ultraviolet, for wavelength smaller than <NUM>, for example between <NUM> and <NUM>), or IR light (infrared, for wavelength greater than <NUM>, for example between <NUM> and <NUM><NUM>).

For example, an exposure source can be a finger (the temperature of which is generally higher than the temperature of a surface of the window), or a lamp.

According to one interesting example, the chromic material turns colourless and transparent under exposure.

Such result can for example be achieved owing to a thermochromic or a photochromic ink.

Such a thermochromic ink is for example water-based or solvent-based, and can use an active principle of liquid crystal type or of leuco-derivative type. Liquid crystal based inks are sensitive to small changes in temperature, but are relatively expensive and difficult to manufacture. Thermochromic materials therefore most often use leuco-derivatives, the complete colour change of which requires a variation of three degrees or more. These compounds are for example encapsulated in gelatine droplets of a diameter of about <NUM> to <NUM>, and of a thickness of about <NUM> to <NUM>. This microencapsulation allows thermochromic substances to be trapped in sealed microspheres which can then be incorporated into aqueous mixtures such as inks, without reacting with their other components. Document <CIT> describes an example of such a thermochromic ink.

Such a photochromic ink can comprise, for example, a spiropyran material, which changes between colourless to colour, reversible.

According to an interesting example embodiment, the chromic material part forms a pattern.

A pattern here includes at least one data, for example, a letter, and/or a number, and/or a symbol, and/or a picture, and/or any other element.

For example, the chromic material part has smaller apparent surface than the OVM part.

According to the invention, at least a portion of the OVM part is superimposed with at least a portion of the chromic material part.

Here, superimposed means that one of the parts is above or below another of the parts, and the part which is below the other part appears covered by this other part from a viewer's point of view, for example if an inspector checks the security document.

According to the invention, the window comprises an additional pattern.

Such additional pattern designates personalized data which further enhances personalisation of the security document, and therefore further improves its security.

According to the invention, at least a portion of the chromic material part is superimposed with at least a portion of the additional pattern.

Such additional pattern is often black coloured, in particular when it is engraved. When it is printed it can be of any colour, as desired and possible.

According to the invention, the window comprises a laser sensitive part in which the additional pattern is engraved.

A laser sensitive part here designates a part of the window comprising a material in which any pattern can be engraved, for example by means of a laser.

For example, the laser sensitive part can be mainly transparent, and preferably colourless.

For example, the laser sensitive part is formed of a layer.

The window comprises at least a transparent part.

The transparent part is possibly colourless.

For example, the transparent part is formed of a layer.

As stated above, the OVM part changes colour depending on the background colour on which it is set.

Such background can be either an independent device, for example like a mat or a board, or it can be part of the security document.

The background comprises at least one colour.

According to one example, the security document comprises at least one background. Thus, the security document comprises at least one configuration in which at least a portion of the OVM part is superimposed with the background.

Integration of both the window and the background into the security document can be done in a so-called "asymmetric way"; for example, the window is integrated in the cavity of body, whereas the background can have a different size, and/or geometry, and/or position in the security document.

According to one example, the body comprises the background.

According to an example, they can be of different sizes, and/or geometries, and/or positions in the body, and the body can be folded so that the window can be superimposed with the background in at least one configuration of the security document.

Otherwise, for example, the background can be positioned in the bottom of the cavity, under the window or backside the window.

In this respect, the body can comprise lenses, like a lenticular lens, on top of the window; for example lenses on top of the document can work together with the chromic, OVM, pattern or a combination of these. Magnification, for example Moiré magnification, would facilitate the authentication, and improve the security of the document. In addition, these lenses enable localized engraving under different angles, for multiple patterns to be inspected. These patterns may include data, including personal data.

Functionalities for at least the OVM part and/or the chromic material part can then be quickly integrated, without relying fully on a background for the window as generated by a handling of an inspector of the security document's authenticity.

According to another example, the window comprises the background.

According to a more specific example, the chromic material part forms at least a portion of the background.

For example, the chromic material part is positioned under the OVM part so that under exposure the chromic material part changes colour, inducing a change of colour of the OVM part.

Such configuration can be combined with a background set in the document, even in the window, or formed of an independent device.

According to one interesting embodiment, the security document can comprise a booklet, like for example a passport.

In such an embodiment, the body in which the window is embedded is for example any sheet, for example the first sheet, of the booklet, and the background is formed, for example, on a backside of a front cover of the security document booklet.

Security documents, like for example an identity card or a passport, can be rapidly authenticated by the colour combinations and changings in one window, either by an inspector directly or by simple additional tools like a mobile phone flashlight, a light source, or a document scanner.

The incorporation of dedicated materials, like inks, in certain positions and locations in the window which contains an OVM permits the above and creates security features that can be authenticated, either complemented through personalization (by adding printed or engraved additional patterns) or not, that respond to induced temperature elevation, or visible, UV or IR or high-intensity light stimulation.

Additional features and advantages of the present invention are described in, and will be apparent from, the description of the presently preferred embodiments which are set out below with reference to the drawings in which:.

<FIG> shows a diagrammatic cross-section of a security document <NUM>, for example an identity document.

The security document <NUM> comprises a body <NUM>, like a sheet or a card body.

The body <NUM> comprises a front side <NUM> and a back side <NUM>.

For example, the front side <NUM> designates a side of the body, which comprises a portrait of a person to who the security document <NUM> belongs, and/or personal data.

The body <NUM> further comprises a cavity <NUM> extending from the front side <NUM>.

The cavity can extend on only a part of the thickness of the body, or go through the entire thickness of the body <NUM>.

Here the cavity extends until the back side <NUM>, so that the cavity crosses the entire thickness of the body <NUM>.

However, in practice, the body <NUM> is set between two transparent and/or translucent layers on either side therefore, one on top and the other below; such transparent/translucent layers are usually called overlays and they cover the internal layers, here referred to as the body, and their security feature.

In addition, lenses, like for example a lenticular lens, can be sit on top of at least one of these two overlays, for example the top overlay.

Thus, the thickness of the body <NUM> is here defined by a corresponding dimension between the front side <NUM> and the back side <NUM>.

The security document <NUM> further comprises a window <NUM>.

The window <NUM> is embedded in the cavity <NUM> which is formed in the body <NUM>, and extends on at least a part of the thickness of the body.

The window <NUM>, in the cavity <NUM>, extends in the body <NUM> from the front side <NUM>.

In the illustrated example, the window <NUM> extends through an entire thickness of the body <NUM>, until the back side <NUM>.

Therefore, the window <NUM> here goes through the body <NUM>.

However, it could extend on only a part of the thickness of the body, and/or from anyone of the sides (front side or back side).

The window <NUM> according to one example comprises mainly an OVM part <NUM> and a chromic material part <NUM>.

The OVM part <NUM> here designates a part of the window which comprises an OVM.

An OVM refers to an optically variable material, for example like the one described in document <CIT>.

Such material can be incorporated in polycarbonate foils, e.g. by compounding and film extrusion.

The OVM is a material which shows colour shifting effects depending on a colour of a background.

In addition, such OVM can be UV fluorescent and then emits one single colour.

For example, the OVM part <NUM> is of a first colour (for example diagrammatically represented in white in <FIG>) when on a white background <NUM>, and of a second colour (for example diagrammatically represented by hatchings in <FIG>) when on a black background <NUM>.

Here, a white background represents a background <NUM> which is white or of any bright colour, while a black background represents a background <NUM> which is black or of any dark colour.

For example, the OVM part <NUM> comprises one specific OVM in polycarbonate.

For example, such an OVM-in-polycarbonate OVM part <NUM> is blue when on white background and red when on black background.

Here, the OVM part <NUM> is formed of a layer.

Here, the OVM part <NUM> comes out on the front side <NUM>. In other word, a surface of the OVM part <NUM> substantially forms a part of the front side <NUM>.

A chromic material part <NUM> here designates a part of the window which comprises a material the colour of which changes from a first colour to a second colour, under an external stimulus, which can be chemical or physical.

Here, the changes of colour are preferably reversible and occur gradually in time, typically in the order of seconds or minutes.

Here, the chromic material of part <NUM> is for example sensitive to temperature or light (which can be general visible light, or UV light, of IR light).

For example, an exposure source can be a warm finger, or a lamp, a UV lamp or an IR lamp.

Therefore, the chromic material of part <NUM> is for example a thermochromic material or photochromic material.

More particularly, the chromic material of part <NUM> is for example a thermochromic or photochromic ink.

For example, without exposure, the chromic material of part <NUM> is of the first colour (for example black), and when the chromic material of part <NUM> is subjected to an exposure, like a thermal or light exposure for example, it is of the second colour (for example colourless and transparent, which is here considered as a colour).

According to the invention, at least a portion of the OVM part <NUM> is superimposed with at least a portion of the chromic material part <NUM>.

Here, superimposed means that one of the parts is above or below another of the parts, and the part which is below the other part appears covered by this other part from a viewer's point of view, for example if an inspector checks the authentication of the security document.

Here, the chromic material part <NUM> is below the OVM part <NUM>.

More specifically, at least in this example, only a portion of the OVM part <NUM> covers the chromic material part <NUM>, and another portion of the OVM part <NUM> surrounds the chromic material part <NUM>.

For example, the chromic material part <NUM> has a smaller apparent surface than the OVM part <NUM>.

The chromic material part <NUM> is for example formed of a pattern. A pattern here includes at least one data, for example, a letter, and/or a number, and/or a symbol, and/or a picture, and/or any other element.

<FIG> illustrates the changes of colour of the window <NUM>, like the one of <FIG>. In this figure, the OVM part <NUM> is represented by a larger circle than the chromic material part <NUM> to facilitate illustration of the changes. However, a cross section of the window <NUM> can be of any shape, preferable rectangle, square, oval or circular for example. The chromic material part <NUM> can also be of any shape as mentioned above, and preferable represents a pattern.

Then, for example, in <FIG>), the window <NUM> is placed on top of a white background <NUM>.

The window <NUM> is in a first configuration which is considered as the natural configuration.

From <FIG>), the window <NUM> is subjected to an exposure, in particular a thermal exposure, like a temperature elevation, or a light exposure, for example a higher intensity of light, and for example of visible light, or UV, or IR. In <FIG>), the window <NUM> is still on top of a white background <NUM>.

In <FIG>), the window <NUM>, while under the exposure, is placed on top of a black background <NUM>.

From <FIG>), the window <NUM> is subjected to a removal of the exposure. In <FIG>), the window <NUM> is still on top of a black background <NUM>.

As mentioned above, OVM part <NUM> is for example of a first colour (for example diagrammatically represented in white) when on a white background, and of a second colour (for example diagrammatically represented by hatchings) when on a black background.

And for example, the chromic material of part <NUM> comprises a thermochromic material or photochromic material which is black in a said natural state (without exposure) and colourless transparent under exposure, in a said excited state.

The colours of the chromic material in either natural state or excited state can be different, depending on the requirement of the contemplated application.

In the present example, as illustrated in <FIG>), the window <NUM> appears of the second colour (for example represented by hatchings) where the OVM part <NUM> is superimposed with the chromic material part <NUM> which is there black, while it still appears of the first colour (represented in white) around the chromic material part <NUM>, where the OVM part <NUM> is superimposed with the white background <NUM>.

From <FIG>), the window <NUM> is subjected to an exposure, in particular a thermal or a light exposure.

For a thermal exposure, the chromic material is preferably a thermochromic material, and for a light exposure, the chromic material is preferably a photochromic material.

A thermochromic exposure is for example a use of someone's finger, which is considered as naturally warm enough to generate a thermal heat of the chromic material.

A light exposure, also said phosphorescence, is for example a use of a light, for example of a different intensity, for example a flash light, or a UV or IR light by a UV or IR lamp.

Then, under exposure, as illustrated in <FIG>), while the whole window <NUM> is still on a white background <NUM>, the chromic material part <NUM> turns from its original colour, for example here black, to a second colour, for example here colourless transparent.

As a consequence, the entire OVM part <NUM> appears superimposed with the white background <NUM> and therefore turns entirely of the first colour.

Still under exposure, the window <NUM> can be moved to a black background <NUM> as illustrated in <FIG>).

Considering the chromic material part <NUM> is still colourless transparent, the window <NUM> now appears superimposed entirely with the black background, and then the OVM part <NUM> entirely appears of its second colour (for example red, diagrammatically represented by hatchings).

If the exposure is removed, after a time depending on the reaction time of the chromic material of part <NUM> for example, the chromic material returns to its natural colour, for example here from colourless transparent to black.

The colour of the OVM part <NUM> depends on whether it is superimposed with the chromic material part <NUM> or with the background <NUM>.

In <FIG>), as both the background <NUM> and the chromic material part <NUM> are black, the window <NUM> is of the colour of the OVM part <NUM> which is of the second colour (represented by hatchings), either where it is superimposed with the chromic material part <NUM> or with the background <NUM>.

Thus, it can be noticed from this example illustrated in <FIG> that the chromic material part <NUM> also plays the role of a background.

Therefore, there can be at least two levels of security, here:.

Referring back to <FIG>, the window <NUM> can also comprise a laser sensitive part <NUM>.

A laser sensitive part here designates a part of the window <NUM> comprising a material in which any additional pattern can be engraved, for example by means of a laser. Therefore, it is usually mainly transparent, and for example colourless.

In the illustrated example, the laser sensitive part <NUM> is formed of a layer. In addition, it is here positioned between the OVM part <NUM> and the chromic material part <NUM>.

According to another example, not illustrated here, the OVM layer <NUM> may also be laser sensitive; hence, the OVM part <NUM> can include at least a part of a pattern which can be laser engraved. In such case, the OVM part <NUM> and the laser sensitive part <NUM> may, in practice, be formed of a same layer. Such can be said "laserable OVM PC".

As illustrated in <FIG>, the window <NUM> can also comprise a transparent part <NUM>.

In addition, the transparent part <NUM> can be colourless.

In the illustrated example, the transparent part <NUM> is formed of a layer.

In addition, the transparent part <NUM> is here positioned under the chromic material part <NUM>. In other words, the chromic material part <NUM> is placed between the transparent part <NUM> and the OVM part <NUM>, and even here between the transparent part <NUM> and the laser sensitive part <NUM>.

Here, a surface of the transparent part <NUM> substantially forms a part of the back side <NUM>.

According to another example not illustrated here, the window may also comprise printings, for example printed on any of the parts of the window. For example, such printings can represent any data.

<FIG> illustrate the security document <NUM> integrating personalization data to enhance the security level. This can also enable certain designs executed in different technologies and principles to enhance security.

Same features bear same numeral references as in <FIG>.

In this illustrated example, an additional pattern <NUM> is engraved in the laser sensitive layer <NUM>. However, the additional pattern <NUM> could be engraved in the OVM part <NUM>, as mentioned above.

As it is engraved, such additional pattern <NUM> is generally black coloured.

For illustration only, the additional pattern <NUM> comprises a word "XX-X".

<FIG>) correspond respectively to <FIG>).

However, in addition, in <FIG>), as the chromic material part <NUM> is there transparent, the additional pattern <NUM> becomes visible.

In <FIG>), as the chromic material part <NUM> is there black, the additional pattern <NUM> is hidden.

The described example relies on a naturally black chromic material part, and a commonly black written additional pattern <NUM>, however same is valid for any colours, providing that a contrast between the colour of the additional pattern <NUM> and the colour of chromic material part <NUM> is low enough for at least a human eye can't distinguish one from the other, the chromic material being in any of its natural state or excited state, depending on when the additional pattern might appear or disappear.

However, the additional pattern <NUM> being usually black laser engraving, it may be difficult to inspect on a black background.

In addition to, or instead of engraved additional pattern <NUM>, same would occur in case of an additional pattern added behind the window <NUM>, such as being printed on a back side of the window <NUM> or on any other support, or even for example on a following sheet of a booklet if the security document <NUM> comprises a booklet, like a passport.

<FIG> shows an example embodiment according to the invention comprising personalization data like in <FIG>.

The embodiment of <FIG> differs from the embodiment of <FIG> in that the order of the part in this embodiment is different: mainly, it comprises two layers of transparent part <NUM> between which the chromic material part <NUM> is positioned.

Furthermore, the window <NUM> of <FIG> comprises a laser sensitive part <NUM> formed of a layer forming a back layer of the window <NUM>.

Thus, both transparent part <NUM> surrounding the chromic material part <NUM> are positioned between the OVM part layer and the laser sensitive part <NUM>.

However, the additional pattern <NUM> here remains superimposed with the chromic material part <NUM>, as in <FIG>. Notwithstanding, in <FIG>, the additional pattern <NUM> is above the chromic material part <NUM>, while in <FIG>, the additional pattern <NUM> is below the chromic material part <NUM>, and the chromic material part <NUM> is between the OVM part <NUM> and the additional pattern <NUM>.

Complementary security can also be achieved by lateral personalization combined with thermochromic or photochromic materials and OVM in ordered layers in the thickness direction of the body.

In <FIG>, same elements bear same numeral references.

<FIG> shows an embodiment in which the window <NUM> is set on a white background <NUM>. At least a portion of the OVM part <NUM> appears of the first colour. The chromic material part <NUM> comprises for example a black ink, which is IR sensitive, which forms a pattern which is here diagrammatically represented by "X-X". Therefore, under an IR lamp, only the pattern, here "X-X", becomes visible. In this example, it appears white. For example, in this case, the window <NUM> can comprise a coloured zone, for example black, to ease the identification of the pattern represented by the chromic material part <NUM> under IR. Such coloured zone can be formed by an additional pattern <NUM> for example, placed below the chromic material part <NUM>.

In such example, the OVM part <NUM> can also be below the additional pattern <NUM>.

<FIG>) show an example embodiment in which personalisation is also realised by engravings.

In <FIG>), the window <NUM> is set on a white background <NUM>. The OVM part <NUM> appears of the first colour, at least around the chromic material part <NUM>.

In <FIG>), the window <NUM> is set on a black background <NUM>. The OVM part <NUM> appears of the second colour, at least around the chromic material part <NUM>. This would be a first level of authentication for example, in which only a different background hue (bright/dark) is used.

At a second level of authentication, the chromic material part <NUM> can comprise, for example, at least a pattern of IR sensitive ink, drawing for example here "X-X" in black under exposure, for example under an IR lamp, as illustrated in <FIG>).

Furthermore, the window <NUM> can also comprise a laser engraved additional pattern <NUM>, here for example representing "T", as illustrated in <FIG>). In this embodiment, when a main part of the chromic material part <NUM> becomes transparent under exposure, it lets appear the additional pattern <NUM>, which can thus be over or below the chromic material part <NUM>.

Considering <FIG>), the chromic material part <NUM> can therefore comprise both a portion comprising a chromic material which turn transparent, and even colourless, under exposure, and a portion comprising IR ink.

The embodiments illustrated in <FIG> also show the non-claimed possibility that the chromic material part <NUM> can be over the OVM part <NUM>, unlike illustrated in <FIG> where the chromic material part <NUM> is under the OVM part <NUM>.

Similarly, in an example (not claimed), the additional pattern <NUM> can be set above the OVM part <NUM> and/or the chromic material part <NUM>, depending on the desired effect.

Claim 1:
Security document (<NUM>) comprising a body (<NUM>), the body comprising at least one side (<NUM>) and a cavity (<NUM>) extending in at least a part of a thickness of the body from the side (<NUM>), and the body comprising a window (<NUM>) embedded in the cavity (<NUM>), the window (<NUM>) comprising at least an OVM part (<NUM>) and a chromic material part (<NUM>), at least a portion of the OVM part (<NUM>) being superimposed with at least a portion of the chromic material part (<NUM>), wherein the OVM part (<NUM>) is a material which shows colour shifting effects depending on a colour of a background on which it is placed, the window (<NUM>) comprises two layers of transparent part (<NUM>) between which the chromic material part (<NUM>) is positioned, and wherein the window (<NUM>) comprises a laser sensitive part (<NUM>) forming a back layer of the window (<NUM>), both transparent part layers (<NUM>) surrounding the chromic material part (<NUM>) being positioned between the OVM part layer (<NUM>) and the laser sensitive part (<NUM>), the window (<NUM>) comprising an additional pattern (<NUM>) engraved in the laser sensitive part (<NUM>), at least a portion of the chromic material part (<NUM>) is superimposed with at least a portion of the additional pattern (<NUM>).