EP0059856A1 - Flat card of thermoplastic material with visually readable security marks, and process for manufacturing the same - Google Patents

Abstract

In order to form safety markings at a planar card made of a plastics material, which card may be used, for instance, as credit card, this card is built up from at least two parts. The inner border area between these two parts comprises a relief-like structure which is the carrier of the safety marking. In order to generate a watermark-like effect the upper part is made of a opaque plastic material and the other part is made of a transparent plastics material. When viewing through this card the areas of the opaque layer having the largest thickness appear as darker areas, whereby when viewing the same way the areas having a smaller thickness show a certain brightness. After being embossed the two parts of the thermoplastic material are joined to each other such that they cannot be separated such that no access from the outside is possible to this safety marking. Accordingly, an additional safety factor is arrived at in cards which can be used as money substrate, identification means or a license for any kind of access.

Description

The invention relates to a flat card made of thermoplastic material with a visually perceptible security symbol, and a method for its production.

Recently, printed cards made of plastic have found widespread use as credit, money substrate and identification cards which convey a service, represent a value or contain an access right. The partial information identifying the carrier and the features which assign the card to a specific organization or system are arranged on the card in the form of imprints, embossings, die-cuts or magnetic, laser or holographic information. It is now relatively easy to recreate the appearance of such cards. It is obvious that there is the possibility of misusing such cards, which are increasingly replacing cash transactions, without requiring too much effort. The public in particular has no way of convincing themselves of the authenticity of such a card.

There are therefore already cards known as _V erbundkarten are configured, wherein a paper layer between two plastic layers included. The paper layer is provided by means of a security print known from the banknotes and, like the banknotes, has a watermark which appears in the review. Furthermore, parts of the plastic surfaces can also be provided with a print pattern.

Although such cards offer increased security, they have several inadmissibilities. As a result of the combination of different materials, such as paper and plastic, experience has shown that the embossing of the finished card causes a deformation. The card is given a curvature in the embossing direction due to the tension that occurs, which impairs the automatic readability of the information mentioned at the outset, provided that it is provided thereon. Furthermore, the structure of the known card offers the possibility of unwanted interventions. For example, the card can be separated along the paper layer, which enables manipulation of this paper layer, or the protective plastic layers can be removed using a solvent, so that the paper layer is then exposed. From such considerations, it is fundamentally undesirable for cards of this type to consist of a paper / plastic composite. Rather, it is desirable to create all-plastic cards that have the necessary security properties. Since such cards must have flat surfaces, however, no configuration has hitherto become known which has security features such as are known, for example, from newer banknotes, in that these often require uneven surface structures. Furthermore, no transparency features have become known for all-plastic cards.

The invention seeks to remedy this. The invention, as characterized in the claims, solves the problem of creating a card which has visually recognizable security features which are enclosed inaccessibly in the card.

The advantages achieved by the invention are essentially to be seen in the fact that the security features are visually recognizable from the outside, but are inaccessible by being covered by a transparent cover card part which is inseparably connected to the card part carrying the features in such a way that that the features are inaccessible for manipulation from the outside.

Two preferred embodiments should be mentioned in particular. In the case of one, the safety sign is preferably perceptible by looking through, in that one of the two parts consists of opaque, the other of transparent thermoplastic, the relief-like structure being such that in certain areas defining a safety sign the opaque part has a locally different thickness having. In the other embodiment, the safety sign is preferably perceptible from above at a suitable viewing angle, in that at least a region of the relief-like structure of the inner boundary surface has a dash-like waveform, this boundary surface being provided with a print pattern such that its visual appearance changes with a changing viewing angle.

• Fig. 1 eine Ansicht eines Kartenteils gemäss einer ersten Ausführung, wie sie sich bei Durchsicht darstellt;
• Fig. 2a eine schematische vergrösserte Schnittan- si,Iht entlang der Linie II-II in Fig. l;
• Fig. 2b eine der Fig. 2 entsprechende Ansicht, wobei die einzelnen Teile vor ihrer Vereinigung gezeigt sind;
• Fig. 3 eine schematische vergrösserte Schnittansicht einer Variante der Ausführung gemäss Fig. l;
• Fig. 4 eine perspektivische vergrösserte Ansicht eines bedruckten Teiles mit wellenartiger Reliefstruktur;
• _Fig. 5a und 5b je eine Draufsicht aus unterschiedlichen Richtungen auf.eine Karte, die aus Teilen gemäss _Fig.4 zusammengefügt ist;
• _Fig. 6a und 6b schematische vergrösserte Schnittansichten von zwei weiteren Aüsführungsformen der Erfindung,
• Fig. 7a und 7b je eine vergrösserte Draufsicht aus unterschiedlichen Winkeln einer Variante der Ausführungsformen gemäss Fig. 6

The invention is explained in more detail below on the basis of exemplary embodiments by means of the accompanying drawings. It shows:

• Figure 1 is a view of a card part according to a first embodiment, as it appears when looking through.
• 2a shows a schematic enlarged sectional view along the line II-II in FIG. 1;
• FIG. 2b shows a view corresponding to FIG. 2, the individual parts being shown before they are combined;
• 3 shows a schematic enlarged sectional view of a variant of the embodiment according to FIG. 1;
• 4 shows a perspective enlarged view of a printed part with a wave-like relief structure;
• _F ig. 5a and 5b are each a plan view from different directions auf.eine card, which is assembled from parts according _F ig.4;
• _F ig. 6a and 6b are schematic enlarged sectional views of two further embodiments of the invention,
• 7a and 7b each an enlarged top view from different angles of a variant of the embodiments according to FIG. 6

Although the different embodiments mentioned above, one of which relates to see-through labeling and the other to top view labeling, are shown individually for the sake of clarity, it should be mentioned right from the start that both embodiments can advantageously be combined, as is shown in FIG. 5 is indicated schematically.

• wobei I : einfallende Lichtintensität o
• I : Lichtintensität nach der Wegstrecke S
• ß : Lichtabsorptionskoeffizient

First of all, versions are described which allow the transparent marking. In Fig. 1, a section of such a card 1 according to the invention is shown in vertical supervision, one having to imagine a light source behind the card. Two zones, which can merge seamlessly into each other, emerge from the rest of the brightness image. A dark zone 4 and a light zone delimiting it. This corresponds to the appearance of the conventional watermark on paper, which is produced by the concentration of paper fibers at certain points, while fibers are drawn off at surrounding points, which creates the delimiting light zones. The different fiber concentrations lead to a different light transmission, which is the cause of the described effect. In the card according to the invention, which is not supposed to have a paper insert but is constructed entirely from thermoplastic, the aforementioned watermark cannot be produced in the manner described. Rather, as can be seen from FIGS. 2a and b, a card is constructed from two half parts 2, 3. The one half Part 2 is made of transparent plastic, the other half part 3 of opaque, ie translucent, cloudy plastic. Such material has an increased light absorption coefficient β, so that the light is noticeably weakened when it passes through a relatively thin layer of, for example, 0.4 mm. One now takes advantage of the fact that the light absorption depends on the distance traveled, according to the law;

• where I: incident light intensity o
• I: light intensity after the distance S
• ß: light absorption coefficient

A larger layer thickness therefore leads to a greater light absorption. The influence of the transparent half part 2 can be disregarded here, since its light absorption coefficient B is negligibly small in comparison with that of the opaque layer. The opaque half part 3 is now formed in such a way that regions 4 of increased thickness are formed to form a watermark-like effect. In contrast, zones 5 of smaller thickness are formed in adjacent areas 5, so that lighter areas 5 are created when looking around the dark-appearing areas, as is characteristic of the appearance of conventional watermarks. In Fig. 2b this is indicated schematically by arrows, which on the one hand represent the uniformly incident light and on the other hand the light passing through, the thickness of the arrows corresponding to the light intensity. The relief in the opaque half part 3 is embossed in such a way that the total amount of material remains constant and only a shift in the amount of material from the areas 5 to the areas 4 takes place. This means that the average thickness over the areas 4 and 5 provided with a relief structure is equal to the thickness of the rest of the map. The impression is taken with an egg ner embossing mold of known type. The transparent half part 2 is provided with a corresponding, opposing embossing, the embossing mold used for this purpose being preferably electrolytically molded from the first embossing mold. The two half parts are then inseparably formed into a single part by laminating. Polymerization of the plastic molecules takes place along the interface of the two half parts provided with the relief structure, so that a molecular connection is formed which makes separation impossible. It goes without saying that graphic patterns can also be printed on the inner interfaces, if this is desired. This will be discussed in more detail in connection with other exemplary embodiments. The surfaces of the card 1 thus formed are flat and can be printed or coated in a conventional manner. The characteristic mark is completely inaccessible in the card. In the normal case, this indicator is not recognizable in the supervision, since the differences in thickness cannot be perceived in supervision alone. This makes it difficult to imitate this characteristic by correspondingly deceptive color printing, as is attempted with conventional watermarks on paper, where, as is known, a small color contrast can also be seen in the top view.

In Fig. 3, an advantageous embodiment of the principle explained is enlarged and shown schematically in section. To do this, the raster technique is used to build up the relief-like structure of the interface. In areas 4, which should appear darker when viewed, the height h _{4 of} the individual punctiform grid elements 7 is chosen to be greater than the height h _{6 of} the grid elements in the main area of the map. In contrast, in adjacent areas 5 their height h _{5 is} chosen to be smaller. The thickness of the opaque half part 3, averaged over the individual areas, is decisive for the light transmission. if the individual halftone dots are no longer or only poorly resolved visually. These averaged thicknesses are chosen so that the effect already explained with reference to FIGS. 1 and 2 can be seen in the review. Again, during embossing, there is only a material shift from the light areas 5 to the dark areas 4. The design of the relief as a grid allows this material rearrangement in a simple manner and also increases the interface along which the two half parts are joined, so that the one-piece map composed of the two half parts is held together even better. The transparent half part 2 is in turn designed to be opposite.

The relief-like interface, which is created within the card 1 with the aid of the explained procedure, can also be configured to identify the card in supervision. If this is to be associated with see-through marking in the manner of the watermark, then one half part must continue to be made from transparent, the other from opaque thermoplastic.

An embodiment which illustrates this is shown in FIGS. 4 and 5. FIG. 4 shows a relief structure of linear construction on the opaque half part 3, a configuration corresponding to FIG. 3 being recognizable in the central region. This structure is printed with a color strip 8, which runs in a straight line in vertical supervision. The opaque half part 3 designed in this way is combined with a transparent half part (not shown) of the same type to form a card, a section of which is shown schematically in FIG. 5. The review is shown in FIG. 5a. The straight line pattern 8 as well as the areas 4 and 5 forming the watermark can be seen. If the map is viewed from an oblique view, as shown in FIG. 5b, the line pattern 8 appears slightly wavy and the watermark disappears. Beige closer inspection in the oblique view, the watermark can still be recognized by the larger amplitude of the corrugation in the line pattern 8. The formation of inspection and supervisory labeling increases the difficulty of counterfeiting such cards and therefore further increases their security.

Finally, a further embodiment of the invention is shown on the basis of FIGS. 6 and 7, which permit identification both in the top view and in the view. 6a and b show two variants of this embodiment in section. The interface between the two half parts 2 and 3 each has a linear grid-shaped relief structure. This is provided with a printed pattern on one of the half parts, the appearance of which changes in the top view depending on the viewing angle (FIG. (Fig. 6b) The first-mentioned variant is based on a relief structure which has at least approximately a rectangular shape 9. The side flanks and valley bottoms are provided with a color layer 10, while the tops remain free of color. In the vertical view, the color areas 10 are essentially perceptible as lines, while in oblique view they merge to form a continuous color area. If colors with low light transmission are used, a different brightness is determined in the view depending on the view angle. With a vertical view, a greater brightness is perceived in the example of FIG. 6a than with an oblique view. In the variant according to FIG. 6b, the relief structure essentially has a triangular shape 11 in cross section. One flank 12 is provided with a color layer 12, while the other flank is free of color. Again, depending on the angle of view, a changed appearance of the print pattern becomes visible, namely changing between mere line pattern (arrow left in Fig. 6b) to a solid color area (arrow right in Fig. 6b). In perception, the perceptible brightness behaves asymmetrically if a color with low light transmission is used. If the card is tilted on the one side from a vertical view, the brightness increases, but when it is tilted on the other side it decreases.

The described _'embodiments can be designed, of course, readily so as to additionally contain a watermark appears in phantom, as explained above with reference to FIGS. 1 to 4. Furthermore, further security features can be provided therein, such as shown in FIGS. 7a and b. This embodiment of the arrangement according to FIG. 6a has a corresponding printing pattern, which, however, is provided with gaps 13 which are arranged in a line in certain directions. In supervision (Fig. 7b), this is not noticeable if this structure is of sufficiently fine design. If, however, a flat viewing angle is selected (Fig. 7a), clearly bright alleys appear in a dark environment. This effect, which is known per se from banknotes, but where an uneven surface is assumed, can easily be used in the manner explained as an additional security feature for flat all-plastic types.

It goes without saying that the flat surfaces of plastic types formed in this way can be printed in the known manner. For the supervision marking according to the described type, windows have to be provided in the print at the appropriate places. Furthermore, parts of the map information can also be present in the print pattern at the interface.

The arrangement described with a relief-like interface, possibly provided with a printed pattern, between two card parts, which are inseparably connected, results in manifold, as shown above partial possibilities of visually securing such cards, which were not previously available. Absolutely flat surfaces are preserved. Embossments in the card do not lead to a curvature, as was the case with the previously known compound cards. The security features are inaccessible to manipulation.

A particularly advantageous application of the see-through marking by means of the relief-like design of the interface of the opaque part 3 and the transparent part 2 according to FIGS. 1 to 3 is that the relief structure is formed in each case according to the portrait of the card owner. This portrait appears in watermark-like form when viewed and can be compared at any time with a photograph of the owner or himself. This enables an additional, individual identifier to be created. This is possible in particular because the relief-like structure of the interface can have continuously merging areas of different thicknesses, which - in contrast to conventional watermarks, which are usually designed in two stages - result in a transparent image with stepless brightness variation between a maximum and a minimum .

Claims (10)

l. Card made of thermoplastic with a visually perceptible security symbol, characterized in that the card is composed of at least two parts (2, 3) lying one on top of the other, at least one of which consists of transparent thermoplastic, and that the inner interface between the two parts has a relief-like structure has, the design of which is such that, when viewed appropriately, at least one safety sign is visually perceptible. 2. Card according to claim 1, wherein the security sign is at least perceptible, characterized in that one part (3) made of opaque, the other (2) consists of transparent thermoplastic, the relief-like structure being such that in certain , A safety sign defining areas (4) the opaque part has a greater average thickness than in adjacent areas. 3. Card according to claim 1 or 2, wherein the security sign is at least perceptible, characterized in that the relief-like structure extends in such a way that the areas defining a security sign have zones (5) which have a lower average thickness than that above the total extent of the opaque part averaged thickness. 4. Card according to claim 2 and 3, characterized in that the relief-like structure has areas of different thickness, which merge into each other continuously. 5. Card according to one of claims 1 to 4, characterized in that the transparent part (2) is formed correspondingly opposite to the opaque part (3). 6. Card according to one of claims 2 to 4, characterized in that at least a region of the relief-like structure of the inner interface has a grid-like shape (7; 9; 11). 7. Card according to claim 1, characterized in that the relief-like structure of grid-shaped elevations (7) are formed on the side of the opaque part (3) which forms the interface, the elevations being of greater height in the areas (4) defining a safety symbol own than in the other areas. 8. Card according to claim 1 or claim 6, wherein the security symbol is perceptible at least in supervision with a suitable viewing angle, characterized in that at least a region of the relief-like structure of the inner boundary surface has a dash-grid-like wave shape (9; 11), this boundary surface with a printed pattern (10, 12) is provided that its visual appearance changes with a changing viewing angle. 9. Card according to claim 8, characterized in that the printing pattern has interruptions (13), the individual interruptions on different shafts being aligned in a straight line with one another, the lines formed in this way extending transversely to the extension of the shafts. 10. The method for producing the planar card according to claim 1, characterized in that by means of an embossing mold on one side a relief in a first section of a thermoplastic plastic composition and by means of a second, correspondingly oppositely shaped embossing mold on one side an opposing relief in a second section of a thermoplastic plastic composition and that the two sections with the embossed surfaces are joined together inseparably.

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