Security document incoporating a security thread.

The invention relates to a security document with an embedded within the document safe_Heitsfad en-To increase the protection against forgery of securities, identification cards, documents, etc. It is known, among other safety features incorporate these also a security thread. For paper products this z. B. is introduced during papermaking in the forming fibrous layer, while being held by the multilayer plastic products between two individual layers. Such security threads can z. B. with machine checkable additives be offset (DE-OS 16 96 245) or have certain optical properties, such. As a different transmission and reflection color (DE-OS 27 43 019).

It is also known to print security threads z. B. with a lettering. Initially film webs are printed and this is then cut into strips. Since the print image register-accurate editing of the film is difficult to achieve, the spacing of the individual Sehriftzüge and the width of the threads is selected so that at least getting a logo completely on the cut thread finds (DE-OS 14 46 851).

Furthermore, it is also known, security threads with a varying optical structure such. As a diffraction grating to use in documents (DE-PS 25 55 214, DE-OS 30 18 238). So that the security document contains a feature. that can not be modeled in a graphic or copy technical reproduction of the document in this form

A disadvantage it proves, in the known Sicherungsmittein that these can be tested either by machine or only under special lighting conditions that the optical effects are only very weakly to detect the viewer only with tools or even just for the expert. In many cases, therefore, is sufficient to provide counterfeit documents with simple plagiarism lower quality in order to simulate the authenticity. Such threads are therefore as simply visually testable authenticity features less suitable.

The object of the invention is therefore to propose a security thread for security documents, said security thread in a simple manner to be without technical aids visually testable and the security thread has to have properties that are lost in a photographic or copy technical reproduction of the document, and methods for providing for the production such security threads.

This object is solved by the features contained in the characterizing part of claim 1. A process for producing such filaments is the subject matter of claim 10.

The security thread according to the invention, which is preferably plastic consists of a transparent material, has usually a rectangular cross-sectional structure and a width of approximately 0.5 mm to 2 mm, wherein in a preferred embodiment, on a surface of a grid of a plurality of parallel cylindrical lenses is embossed. The thickness of the security thread is chosen such that it corresponds approximately to the focal length of the cylindrical lenses. On the opposite surface of a printed image is applied. The printed image is designed in consideration of the optical properties of the cylindrical lenses. Due to the focusing effect of the cylindrical lenses and the position of the print image in the focal plane of the printed image are visible depending on the viewing angle different subregions.

By appropriate design of the print image information can be introduced that are only visible under certain angles. However, it is also "moving" images are generated, the printed image is designed such that upon rotation of the document a subject moves on the security thread to another location a to the cylindrical lenses parallel axis almost continuously from one location.

In the preparation of these security threads, therefore it should be ensured that the pressure strips are applied in precise alignment to the cylindrical lenses on the carrier sheet. Particularly when using cylindrical lenses with small lens width (100 u), the creation of a sufficiently fine print image and the register exact printing of the individual strip images in relation to the cylindrical lenses high requirements.

With special printing techniques (eg. As by the film gravure or Näpfchentiefdruck method) and appropriate procedures are also an object of the present invention, but it is possible to produce so-called micro-printed images and to apply them in exact register to the cylindrical lenses on the support. Thus it is now possible to use such elements as security elements and to embed them in the form of threads in security documents. Because of its difficult technical design this thread you distinguished from rch a particularly high security against forgery.

The security thread according to the invention has the further advantage that it can be provided with a safety quality microprinting image, said with the naked eye is very difficult resolvable print image without technical aids can be tested per se, since it is now increased by overlying cylindrical lenses.

The security thread can be embedded by the conventional methods in the security document. When embedding .in paper to better visualize preferably windows are incorporated into the yarn overlaying paper layer. Securities with exposed pane threads and processes for making them are for. Example, from DE-PS 214 838, DE-PS 314 970 or DE-OS 27 43 019.. The yarn can also be embedded so that it is covered only by a thin paper layer, so that the visibility of the thread is only slightly restricted.

Through the overlying layer of paper, the surface structure of the filament is protected from abrasion at the same time. In addition, the threads adhere in particular, in which the cylindrical lenses extending transverse to the thread direction, very good in the paper, since the yarn structure and the paper fiber mesh structure. Such a thread can not be "pulled" from the paper without damaging the paper sheet.

The threads are preferably self-prepared so that on wide film webs initially memorized the cylindrical lens grid and then to the opposite side of the film, the print image is printed. This foil webs are then cut into individual strips having the desired security thread width.

These cylindrical lenses are (printing, cutting) used in the invention for alignment and adjustment of the film in the following processing steps. The guide elements (rollers, cylinders, etc.) of this application only coming in tools such. As the printing or cutting device, are designed for this purpose with a for lenticular complementary relief structure. During the passage of the film by these guide elements, the lens array and the relief structure engage with each other, so that the sheet when passing in the exact geometric association to the printed lenticular, cut or still can be otherwise processed.

The inventive method sheets can now register accuracy in a simple manner and especially over long distances to an on the opposite side of the embossing pattern are printed. In the same way this embossing pattern can also be used for register exact cutting the film into individual strips which may then be embedded as security threads into banknotes or identity cards.

This process can also be prepared other security threads with small widths (about 0.5 mm), z. B. an along-end extending, z. B. multicolor having print pattern. Here grooves are impressed in the distance to the desired width of security threads in the first step in a film. Printing is carried out thereafter, the film is oriented using these grooves over the printing units and z. B. applying a printed image on the smooth film surface the grooves opposite. After printing, the film is again cut in relation to the position of the grooves into individual strips. The film strips thus produced then have the external dimensions of the strips exactly plaziertes print image.

Further advantages and advantageous developments are the subject matter of the dependent claims and the description with reference to FIGS.

The figures show:<ul><li>FIG. 1 a security with an embedded security thread is a sectional view,</li><li>Fig. 2 shows a security thread according to the invention in a sectional view,</li><li>Fig. 3 is a schematic representation of a specific embodiment,</li><li>Fig. 4 is a schematic diagram of a apparatus for producing these security threads,</li><li>FIG. 5a, b a film and a corresponding guide roll,</li><li>Fig. 6 cutting device,</li><li>Fig. 7a, b show another film with corresponding guide roller.</li></ul>

Fig. 1 shows an inventive security document 1 in a sectional view. The security document is z. B. a bill or a stock, consisting incorporated from a single- or multi-ply paper layer, inside which a security thread 2. The security thread is made of a transparent material, eg. B.

Plastic, in which one surface is a relief structure 3 imprinted in the form of several parallel juxtaposed cylindrical lenses 4 (Fig. 2). On the opposite surface of a printed image is applied, which, in principle, as shown in FIG. 2, a plurality of individual strips, z. B. three strips a, b and c, composed. The one zeins strips are different. Viewing angles, are seen separately. the security thread Are the strips z. B. single color stripes with different colors, so change with gentle tilting the document color. The printed image can also be designed so that the individual disputes, which are visible under a viewing angle at the same time, such as those marked with a) strip, a thread over the entire width and -. Play length extending motif. The thread can thus involve several, among other independent information in themselves, which are then separated under different Berachtungswinkeln read.

Another design option is shown in FIG. 3, the cylindrical lenses 4 here extend transversely to the thread direction. A motive for. Example, a ring 6 is printed in repeating intervals in correlation to the cylindrical lenses that its location on the thread with the viewing angle changes shifts and the subject is second with gentle tilting from a first position A to a position B. The viewer is thus give the impression of a "moving" image. The design, in this case a ring, must also naturally be decomposed into corresponding strips images and this Enzelstreifen be printed with respect to the location of the cylindrical lenses so that composed these strips when viewing the thread through the cylindrical lenses into a ring and its position on the thread by changing the viewing angle shifts the Frnzelsireifen that contribute to the representation of a ring, are printed offset therefrom in the direction of the thread each by a specific distance relative to the cylinder lens center. The use of Kippbildeffekte on striated security threads is of course also possible, such as the motion picture effect at fängsgesfreiften threads. A combination of both effects on a security thread is also conceivable.

The thickness d of the security thread and the radius of curvature of the cylindrical lenses is chosen in dependency of the refractive index of the thread material so that the printed image lichst in the focal plane of the cylindrical lenses is pos.

Security documents such. As banknotes generally have a thickness of about 100 u. The thread embedded therein should have a total thickness d of about 70 u. Not exceed. The required radius of curvature of the cylindrical lenses is calculated assuming a refractive index of 1.5 of the thread material, such as plastics common practice according to the formula d = 3 xr = f, where f is the focal length of the lens. In the said film thickness is accordingly obtained about 20 lenses per mm. The strip shown in Fig. 2 a, b, c (rather than characters, etc.) are in this case with a respective strip width of about 16 μ to be printed-Selects at a film thickness of about 70 μ, a lenticular lens of 10 elements per mm ensprechend larger radius of curvature, so the individual strips of the printed pattern on the one hand only weider given more focus, which on the other hand the possibility to imprint the strip of double width, which is technically easier to implement. Since the strip anyway only allow a homogeneous color impression over the entire lens width, this blurring of the lines across the width of the security thread in the overall impression is not disturbing.

Although in the latter embodiment, the strip width can be about 30 u, provides such a pressure pattern still the highest demands on print quality. For equipped with simple means counterfeiters such a printing pattern is incomprehensible. Despite this fine line pattern, the security thread, however, is from the viewer testable without aids such as magnifying glasses or the like, as for him among their respective viewing angles large color effects can be recognized, each über'die whole Secure unit bland wide extend.

Instead of the cylindrical lenses, other embossed structures, which also have a focusing effect, z. B. spherical lenses or honeycomb lenses, are provided. The image is then of course adjust the optical conditions of each type of lens.

Furthermore, instead of the lenses and optically similar effect measures are taken to achieve the viewing angle-dependent, is changing appearance of the yarn. Thus, for example, a security thread, consisting of a transparent film can be printed on both sides, the printed data from one side of the film is designed so that it to the viewer depending on the viewing angle -. The dates are different areas the viewer remote back print image of the thread. So z. B. is printed the forming the security thread foil on one side with a line grid or a negative dot grid. This grid act with appropriate Dimensionsierung the grid structures and the film thickness as aperture, narrow the field of view, so that depending on the viewing angle only certain limited areas of the opposite film surface are visible. Designed to the lying on the opposite film surface printed image corresponding to this aperture structure, the production of security threads is possible to change with variation of viewing angle their visual appearance such. As the color, design etc.

In a further Ausführungsfarii, the optical structure, such as, for. Example, the lens structure is applied to two opposite surfaces of a substantially rectangular security thread, and accordingly the print image is preferably arranged in the middle plane of the thread. The opposing lenses can thereby be gleichgeartet and congruent and are arranged offset zeuinander.

FIG. 4 shows an apparatus for the production of security threads, in which the cylindrical lenses extend in the longitudinal direction of the thread.

A wide film web 7 is taken off from a supply roll 8 and an embossing station 9 fed in the z. B. means of a calender roll 10 and a counter roll 11, the cylindrical lenses are impressed in the longitudinal direction to the film web. The embossed sheet is then deflected over a guide roller 12 and the pressure device 13 which in the aufdie unembossed side of the film, the printed image is applied. The printing apparatus 13 includes one or more print cylinder 14 with opposed counter-rollers 15, the sheet may again be fed via guide rollers between the individual printing cylinders in order to ensure register-exact guiding of the film to the individual printing units. For drying, the pressure, the film is then passed to a drying station 16th so that the film can be supplied by reversing via a further Führungsfolle 17 a cutting station 18th There, the film web is cut into strips or threads 19 and wound, the strips or threads on separate rollers 20th

According to the invention, the guide rollers are at least 12 and 17 equipped with a negative to that in the embossing station incorporated in the film lenticular relief structure 21st In Fig. 5a the film is shown with the embossed cylinder lenses 4 and in Fig. 5b to corresponding guide rollers 12 and 17 with the corresponding negative structure 21. These guide rollers are in solid, spatial assignment to the printing or cutting devices mounted, so that it is ensured in this way that the film is always printed and cut in the correct geometrical assignment to the cylindrical lenses are already on the slide. For better guidance of the film, the film on the guide rollers 12 and 17, preferably around 90 °, is deflected in order to obtain the greatest possible angle of wrap.

Fig. Figure 6 shows a cutting device 18 preferably used is cut by means of the foil web into individual narrow strips. The cutting device consists of a plurality of respectively mounted on two rotatable shafts cutter discs 22, 23 which engage into each other. The width of the discs corresponding to the desired filament width. In order not to destroy the lens structure on the film, the face of the discs 23, which come into contact with the embossed side of the film, milled. Simultaneously, the cutting action of the discs is increased by this milled recess.

. In addition to the guide rollers, for example, can before the printing or cutting devices are mechanical or optical scanning elements - (in the figure not shown.) Are provided which similarly engage a pickup in the grooves between the lenticules and monitor the run of the film web. Optionally, subsequent adjustments can be made smaller in the course of the film web due to the scanning signals.

In the preferred embodiment shown here, the various machining operations such as embossing, drukken and cutting are carried out in direct succession. However, the individual machining operations can also be carried out spatially and temporally independent of each other. For this, the already revised partly foil is rolled onto storage reels and latched until the next processing operation. Since the film is provided in the first machining operation with the lenticular and the subsequent operations are managed using this lens array, a separation of the individual machining operations is possible.

According to this method it is thus possible - to produce narrow strips or filaments, which have a print image in register over long lengths, that runs exactly positioned in the longitudinal direction of the strip and also placed exactly to the external dimensions of the thread or to the center of the thread is.

When the paper web producing security threads are continuously embedded in the sheet-forming fibrous layer or between two layers of paper is still moist. Since this process as little as possible is to be interrupted, it is precisely here required that the threads are in accordance with long lengths (several kilometers). This means, however, that the threads have to be printed on the same routes in accurate register to the cylindrical lenses and cut. The inventive method, these requirements can be met, so that the way is opened to take advantage of the visual effects for FAEL research safe design of security threads described, these effects are imitated easily and without optical Hitfsmittet prüfaar and only with great effort technotogischen.

However, this method can equally well find application for the production of yarns which should have only one side along one of the thread extending pressure pattern or surface structure and on the opposite side a smooth surface.

As shown in FIG. 8a for. example, the later thread width or an integer multiple thereof to in the film web 7 at certain intervals corre Chen, grooves 24 embossed, that run along the Foüenbahn. For further processing, the film is over guide rollers 25 (Fig. 7b), is incorporated into the turn, the negative pattern of grooves 26, aligned and adjusted so that an accurate printing, embossing, milling and / or cutting operations in dependence on the position of the grooves , These grooves can also be formed so deep that they simultaneously serve as tear lines, along which the film can be separated after processing into individual strips. The inventive method for accurate register processing of films can also be used to two and to store more films in exact mutual alignment above one another and then to glue or weld or apply already provided on a z. B. with a printed image surface.