EP0628431B1 - Multilayer record carrier and process for marking a multilayer record carrier - Google Patents

Abstract

For multicolour marking of identity cards and the like, the multilayer identity card is provided with an outer coloured layer in a first colour and an inner coloured layer in a second colour. While the outer coloured layer absorbs virtually none of the laser light used for marking, the second, inner coloured layer absorbs the laser light. This causes the material in the second coloured layer to be thermally degraded, i.e. evaporated, sublimed or subjected to a chemical or physical reaction, during the marking operation, with the consequence that formation of pressure causes the first layer to be broken up into particles, causing the second coloured layer to become visible. The second coloured layer may also be replaced by a transparent coat of varnish having appropriate properties in order to expose, for example, a multicolour security printed image under this transparent coat of varnish. <IMAGE>

Description

The invention relates to a record carrier according to the preamble of claim 1, in particular an identification card and method for labeling such a record carrier.

In a special case, the record carriers in question here are identity cards, e.g. B. credit cards, credit cards, authorization cards or business cards and the like. Identity cards of this type have a format prescribed by standards and generally have a multilayer structure. On one side of the card are e.g. B. by printing or general photographic information, e.g. B. the name of a credit institution, an organization or the like, as well as possibly a security print image (guilloche pattern), which is placed on the card surface or inside the card. In addition, the user-related information such as the name of the card holder, customer number, account number, card number or the like is introduced.

For the colored labeling of multi-layer ID cards, it has already been proposed (DE-PS 30 48 733) to provide differently colored layer areas one above the other, the absorption behavior and the evaporation points of the individual color layers being chosen such that selective control of the ink layer is achieved by appropriate control of the laser beam intensity. The outermost layer of paint is therefore removed at lower laser beam intensities than the deeper layers of paint.

Identity cards of this type already have improved protection against counterfeiting and falsification. However, there is still a need to further improve such record carriers, in particular with regard to their security against forgery, so that the object of the invention is to provide a record carrier and a method for its labeling in which the security against counterfeiting is considerably increased.

The solution to this problem is specified in the independent patent claims.

In the prior art, the upper first layer of a multi-layer recording medium reacts to the incident laser beam and is removed in order to expose the second layer underneath and to make its color visible from all viewing angles. In the record carrier according to the invention, however, a surface is structured in such a way that information can be introduced with the aid of a laser beam in such a way that it shows different appearances, depending on the respective viewing angle.

In addition to the viewing angle-dependent effect, which in itself considerably increases the security against forgery of the data carrier, such a data carrier also has the advantage that the inscriptions introduced with the aid of a laser beam cannot be achieved with simple mechanical means, such as by mechanical engraving methods.

Interesting visual effects can be achieved if the relief structure is printed by e.g. B. arises from gravure printing or a relief structure is embossed, which continues over the layers above. These relief-like surfaces can be labeled in the same way as smooth surfaces according to the inventive method. The security against forgery of laser engraving (lettering) is particularly important here, since structures of this type cannot be labeled in this simple form using mechanical engraving, which is known per se.

If the laser beam is aimed at this relief-shaped surface at an acute angle below, the recorded information changes its appearance depending on the viewing angle and, in extreme cases, is only visible from the side from which the recording was made.

The marking of a record carrier with a laser beam, which forms an acute angle to the record carrier, is particularly effective if the record carrier has passed with an embossed structure in the form of, for example, a corrugated iron structure, half cylinders, hemispheres, lens elements or the like. This is because the laser beam can first be guided over the embossed structure in a certain direction at a certain angle with respect to the plane of the recording medium. Only the "slopes" of this embossed structure facing the laser beam are labeled. If you then rotate the record carrier in its plane and then guide the laser beam over the embossed structure at the same or a different acute angle, the "slopes" of the embossed structure are labeled with the laser beam once from one side and once from the other side, correspondingly the label direction is a different picture when viewed from the corresponding direction if the different sides of the embossing structure are designed accordingly. It is thus possible to generate different images for different viewing directions on opaque surfaces, these images also being able to be viewed separately from one another depending on the viewing angle, or complementing one another with a vertical viewing angle.

Fig. 1

eine Skizze, die den Stand der Technik veranschaulicht,

Fig. 2

eine Ausführungsform eines Aufzeichnungsträgers im Querschnitt,

Fig. 3

einen unter einem spitzen Winkel beschrifteten Aufzeichnungsträger,

Fig. 4

eine Skizze, die das Abtasten eines mit einer Prägestruktur versehenen Aufzeichnungsträgers mit einem Laserstrahl unter einem spitzen Winkel veranschaulicht und

Fig. 5

eine Draufsicht auf eine Ausweiskarte mit verschiedenen Reliefstrukturen.

Exemplary embodiments of the invention are explained in more detail below with reference to the drawing. Show it:

Fig. 1

a sketch illustrating the state of the art,

Fig. 2

an embodiment of a record carrier in cross section,

Fig. 3

a record carrier labeled at an acute angle,

Fig. 4

a sketch illustrating the scanning of a recording medium provided with an embossed structure with a laser beam at an acute angle and

Fig. 5

a plan view of an identification card with different relief structures.

Fig. 1 shows a part of a known ID card in cross-step (DE-OS 30 48 735), which is here z. B. can be a check card. Two color layers B and C are applied to a base layer A. For the sake of clarity, the map layers are shown in this and in the following figures in a form that is not to scale. These two layers of paint differ in their color and in their absorption properties and evaporation points. Since the layer thicknesses at different points are not always exactly uniform, but fluctuate within certain limits and the evaporation points are usually relatively close together, the dosage of the laser beam intensity is a problem for the exposure of the desired color layer. The layers are therefore preferably removed step by step in a plurality of irradiation processes with a correspondingly low intensity in order to expose one layer in a targeted manner and not to cause an incomplete or complete removal together with further layers in an undesired manner. For example, several, e.g. B. two, labeling steps (D, E) to remove an area in the layer C performed. Then, if necessary, further labeling steps (F, G) for removing a location of layer B are carried out. In this way, multi-colored representations are generated in several process steps.

In FIG. 2 there are embossments 34 running into a base layer 31 into the plane of the drawing, on the outside there is a continuous first color layer 33 which hardly absorbs laser light, and below the first color layer 33 there is a second color layer 32 (this can also be transparent) ) that the laser light absorbs. Individual areas of the color layers 32 and 33 are removed by scanning with a laser beam. The second color layer 32 can also only be removed to a certain depth so that its color is visible or replaced by a transparent lacquer layer sensitized in the form described above by admixing pigments. In the latter case, the top of the base layer 31 or the embossments 34 is then visible in the labeled areas.

In Fig. 3, the laser beam strikes the identification card at an acute angle, as shown by the arrows P in Fig. 3. The structure of the hardness according to FIG. 3 is similar in principle to the structure according to FIG. 2. However, due to the oblique irradiation with laser light, only the inclined surfaces 35 of the embossments 34 facing the light source are “labeled”, while the inclined surfaces 36 facing away from the light source are hardly or at all not be affected by laser light.

The acute angle between the incident laser beam and the identity card plane means that the outer color layer 33 is visible from one side (from the left in FIG. 3), while the other is visible Side (right in Fig. 3) mainly the areas exposed by the inscription with laser light are visible.

FIG. 4 shows another representation of a layer 41 provided with an embossed structure 42 (alternating field shape). According to the above-mentioned structure according to the invention, z. B. a transparent, thermally degradable lacquer layer 45 and an outer color layer 46 thereon. B. line-shaped the substrate 41 is exposed on the inclined surfaces 35 of the embossed structure 42 shown in FIG. 3 and facing the laser. With a z. B. line-shaped recording process, only sections 44 a b, c are exposed in a scanning line 44 due to shadowing by the embossed structures. The result is a direction-dependent image that cannot be reproduced in this form in terms of copying technology or photography.

If the recording medium is subsequently rotated through 180 ° or the laser beam is deflected accordingly, a further labeling process can follow, in which another image, possibly in a different color, is introduced onto the opposite inclined surfaces 36 of the embossed structure by exposing deeper layers (not shown).

As shown in FIG. 5, such optically varying images can be applied over a large area to an identification card 50 by providing the entire card with, for example, individual embossing lines 51 which run through the card and essentially follow a predetermined direction. However, only a partial area of the card can be provided with an embossed structure 52, the embossed structures, as shown in FIG. 4, directly against one another adjacent in continuous form. This area can e.g. B. can be labeled from different directions with different image motifs, which in turn can only be seen separately from the respective recording direction and can complement one another when viewed vertically.

The exemplary embodiments described considerably increase the security against forgery of the identity card. Engraving of this type, which due to the measure according to the invention of removing partial areas of an upper ink layer as extremely sharp-edged labeling areas on an uneven surface, cannot be achieved with simple means by mechanical engraving means.

In principle, the creation of such "images with directional effect" by labeling relief structures at an acute angle of incidence even with conventional card structures, such as. As shown in Fig. 1, possible, but the cards can also have only a simple opaque, structured surface or surface labeling, which discolors under the action of a laser beam. The information is not generated by removing layers and exposing deeper, color-contrasting layers, but by directly changing the color of an outer plastic or color layer.

Claims (2)

1. A data carrier, in particular identity card, having an outer layer or coating which visibly changes its color or contrast with the surroundings under the action of a laser beam, characterized in that at least this layer has a relief structure, preferably in the form of semicylindrical elements, hemispherical elements, corrugated structures or the like, and information is recorded at an acute angle to the data carrier plane in the area of said relief structure by means of a laser beam, the slopes of the relief structure facing the recording direction being inscribed differently to the slopes facing away therefrom so that the information thus recorded appears in different forms depending on the particular viewing angle.
2. A method for inscribing a data carrier, in particular identity card, having an outer layer or coating which visibly changes its color or contrast with the surroundings under the action of a laser beam, characterized in that a relief structure, preferably in the form of semicylindrical elements, hemispherical elements, corrugated structures and the like, is incorporated at least in this layer, and information is recorded at an acute angle to the data carrier plane in the area of said relief structure by means of a laser beam, the slopes of the relief structure facing the recording direction being inscribed differently to the slopes facing away therefrom so that the information thus recorded appears in different forms depending on the particular viewing angle.

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