EP1459268A2

EP1459268A2 - Valuable document

Info

Publication number: EP1459268A2
Application number: EP02790486A
Authority: EP
Inventors: Reinhard Plaschka; Johann Müller; Roger Adamczyk; Peter Franz
Original assignee: Giesecke and Devrient GmbH
Current assignee: Giesecke and Devrient Currency Technology GmbH
Priority date: 2001-12-17
Filing date: 2002-12-12
Publication date: 2004-09-22
Anticipated expiration: 2022-12-12
Also published as: PL216389B1; RU2324599C2; JP2005512846A; WO2003052702A2; DE10162050A1; MXPA04005875A; BR0215078A; AU2002366437A1; PL369547A1; CN100346360C; CA2473879C; WO2003052702A3; RU2004122122A; EP1459268B1; EP1459268B9; AU2002366437B2; CA2473879A1; US20050115425A1; CN1605089A

Abstract

The invention relates to a data carrier on which a tactile continuous-tone image is imprinted, to a method for producing said data carrier and to a die plate which is suitable therefor.

Description

value document

The invention relates to a data carrier printed with a tactile halftone image, a method for its production and a printing plate suitable for this.

Data carriers in the sense of the invention are, in particular, security or value documents, such as banknotes, identity cards, passports, check forms, shares, certificates, stamps, flight tickets and the like, as well as labels, seals, packaging or other elements for product security. The simplified term "data carrier" and "security or value document" therefore always includes documents of the type mentioned below.

Such papers, whose commercial or utility value far exceeds the material value, must be recognizable as genuine by suitable measures and distinguishable from counterfeiting and counterfeiting. They are therefore provided with special security elements, which ideally cannot be imitated or can only be copied with great effort and cannot be falsified.

In the past, those security elements that have been identified by the viewer without aids and recognized as genuine have proven particularly useful, but at the same time can only be produced with great effort. These are, for example, watermarks that can only be inserted into the data carrier during paper production, or motifs produced using intaglio printing that are characterized by their characteristic tactility, which cannot be imitated by copying machines. The line or intaglio printing technique, in particular the steel intaglio printing technique, is an important technique for printing on data carriers, in particular securities, such as banknotes and the like.

Intaglio printing is characterized by the fact that line-shaped depressions are made in the printing plates in order to produce a printed image. The ink-transferring areas of the printing plate are thus present as depressions in the printing plate surface. These depressions are produced using a suitable engraving tool or using etching. In the mechanically manufactured printing plate for intaglio printing, a wider line is created with increasing engraving depth due to the usually tapered engraving tools. In addition, the color absorption capacity of the engraved line and thus the opacity of the printed line increase with increasing stitch depth.

When etching intaglio printing plates, the non-printing areas of the printing plate are covered with a chemically inert lacquer. Subsequent etching produces the engraving in the exposed plate surface, the depth of the engraving lines depending in particular on the etching time. Before the actual printing process is done on the engraved

Printing plate ink pasty consistency applied and the excess printing ink removed from the surface of the printing plate by means of a doctor blade or a wiping cylinder, so that the ink only remains in the depressions. Subsequently, a substrate, usually paper, is pressed against the printing plate and in the process also into the depressions of the printing plate filled with ink and removed again, the color being pulled out of the depressions of the printing plate, adhering to the substrate surface and forming a printed image there , If glazing colors are used, the thickness of the paint application determines the color tone. So you get when printing on a white data medium with thin layers of ink, a light color tint, when printing with thick layers of color, darker shades. The thickness of the ink layer is in turn dependent to a certain extent on the depth of the engraving.

The line intaglio printing technique allows a relatively thick ink application on a data carrier in comparison to other common printing techniques, such as offset printing. The comparatively thick ink layer produced using the line intaglio printing process, together with the partial deformation of the paper surface that is caused by pressing the paper into the engraving of the printing plate, can also be easily felt manually by laypersons and is therefore easily recognizable as an authenticity feature based on its tactility. The tactility cannot be imitated with a copier, so that the line intaglio printing technique offers high-quality protection against counterfeiting.

These printed images can only be printed over the entire area with a special additional effort, since the non-engraved areas of the printing plate usually do not transfer any color to the paper to be printed, so that the printed image is normally always limited to motifs composed of narrow lines. A combination of full-surface printing with tactility is not possible with conventional intaglio printing.

A further gravure printing technique is differentiated from engraving or line gravure, namely screen gravure. It is characteristic of screen gravure printing, in particular for autotypical screen gravure printing, that different gray or color values of the printed image are generated by cups of different density, size and / or depth spaced apart and spaced apart in the printing plate. At grid depth Printing processes are used to produce the printing plates mechanically, for example, using stylus tools or by ablation using an electron beam or laser beam. Typically for gravure printing is the use of thin ink and a squeegee. The principle of the printing process is based on the fact that the cells are filled with the thin liquid and the color is kept in the cells of different depths. The grid bars that limit the cells serve as a support for the squeegee, but are not themselves printing. When printing, however, due to the thin liquid of the ink, the boundaries between the adjoining printing areas run so that they can no longer be separated exactly. A quasi full-surface print image results. However, the lack of toughness of the printing ink and the low contact pressure prevent the formation of relief, so that the printed image also has no tactility.

Conventional halftone and line intaglio printing therefore have the disadvantage that tactility cannot be achieved in one print run with simultaneous full-surface printing.

The object of the present invention is to provide a data carrier with increased protection against counterfeiting, which has both a tactile and an image motif that is difficult to imitate in terms of printing technology and visually conspicuous, since it is produced by intaglio printing.

Another object is to provide a printing plate for producing the data carrier printed according to the invention and a corresponding production method.

This task is solved by the independent claims. Further training is the subject of the subclaims. The invention is based on the fact that the print image provided on the data carrier and produced by intaglio printing represents a halftone image. In at least one partial area of the image, this halftone image comprises printed partial areas directly adjacent to one another, the partial areas having specific tonal values and at least a partial area of the image being tactile perceptible.

In the context of the invention, “halftone image” refers to an image which has intermediate tones between the lightest and darkest image point. If it is a black and white image, “tonal value”, as usual, is a value on a gray scale from white to black to understand. However, the present invention relates not only to black and white halftone images which contain the achromatic colors, namely white, black and gray, but of course also to monochrome or multi-color halftone images which comprise the so-called bright colors. In the case of the colorful halftone images, “tonal value” is to be understood as the brightness of the color under consideration. The image according to the invention preferably comprises at least three tonal values. If the basic color of the substrate to be printed, for example the white of the paper, is incorporated into the design of the image, The image preferably has four tonal values, for example white, black and two gray values. In particularly preferred embodiments, the printed image has a significantly larger tonal value range, so that in addition to light and shadow effects, plastic effects can also be achieved , ie the larger the tonal value scale, the better the motifs can be represented spatially and, ideally, the printed image approximates a photographic representation, whereby the tonal value gradations merge almost continuously into one another, however, experiments have shown that four halftone levels already give a very realistic halftone impression at se For the layperson, the difference between halftone levels and the photographic halftone image is only relatively slight. The halftone image can represent any motif. However, visual representations are preferred. However, the portrayal of portraits is particularly preferred, since human perception is trained for the finest differences in portraits and the recognition value and thus the security value of this security element is particularly large. Multiple halftone images can be combined in any number and shape.

Since conventional intaglio printing inks are to a certain extent glazed and translucent, suitable layer thicknesses and a sensible choice of the color of the background result in color or gray tones of different brightness and color saturation. The different brightnesses in the sense of the invention, hereinafter referred to as “tonal values”, can thus be generated solely via the ink layer thickness, ie the printed partial areas of different tonal values are printed with an ink layer of different thickness. This results in the printing of a white data carrier with small ink layer thicknesses light colors, darker colors when printing with thick layers of color. It is also not excluded that depending on the printing ink and substrate used, depending on the layer thickness, the color saturation as well as the brightness can change. Normally, however, the color layer thickness mainly affects the brightness value and the The influence of the layer thickness on saturation and brightness has to be determined accordingly in each individual case, ie for each color and each substrate Highly visible contrasts without additional aids. Normal lighting conditions and a normal viewing distance are assumed.

In order to produce a printed image according to the invention, a template, preferably a portrait, in partial areas related to halftone values is first tert rushes. Different engraving depths for the printing plate to be produced are then assigned to the individual tonal values or groups of tonal values of this implementation, coordinated with the printing ink used. For example, maximum engraving depth for black and minimal engraving depth or unengraved for white. Accordingly, all tonal values of the original are to be converted into corresponding engraving depths on the printing plate. The engraving depth of the printing plate required to generate a special tonal value varies from printing ink to printing ink.

Which assignment is necessary can be easily determined by printing a graduated gray wedge with the printing ink under discussion. The gray wedge has a large number of surface elements for this purpose, which are lined up and differ in defined engraving depth steps. If, for example, the engraving depth is varied in 5 μm steps, the gray wedge begins with a field with 5 μm engraving depth, the next field has an engraving depth of 10 μm, the next 15 μm etc. up to an engraving depth of e.g. 100 μm. The field size is, for example, 5 x 5 mm. The individual fields are separated from each other only by narrow dividing edges.

If you now print the gray wedge with a special color, you will find that the first field has a special light tonal value that contrasts with the next field, whereby the next fields each have darker tonal values up to a field in which the darkest tonal value is available. From this field there is no longer any tonal variation. Depending on how many tonal values are to be used in the halftone image to be printed later, these are assigned to the respective fields of the gray wedge, which then also gives the engraving depths required for the production of the printing plate. This gray wedge test must be carried out separately for each printing ink. If a printing ink has too little "transparency bandwidth", ie too few tone values contrasting with increasing engraving depth, these can be adapted by measures known to the person skilled in the art.

If you print a halftone image in which the engraving depths of the tonal value areas are matched to the transparency of the printing ink, you get a halftone resolution without the usual screen technique. The tonal values are based solely on the transparency of the colors. In addition, the printed halftone image also has a surface relief in which the darker areas are higher than the light areas.

For the purposes of the invention, “partial areas” refer to areas from which the halftone image is composed. The partial areas are printed and possibly unprinted areas, with at least some of the printed partial areas directly adjacent to one another. “Directly adjacent to each other” means that the adjacent areas are not separated by unprinted areas. The proportion of the printed partial areas in the halftone image printed according to the invention is preferably greater than the proportion of the unprinted partial areas. Furthermore, the printed partial areas are predominantly adjacent to one another, so that the halftone image printed according to the invention gives the impression of essentially full-area printing. The adjoining partial areas can have different tonal values, ie different color layer thicknesses, but also the same tonal values, ie same color layer thicknesses. In particular, unprinted areas are mainly used for design purposes, for example to display light reflections or shiny spots. The security against forgery of the security element or security print image according to the invention can finally be increased further by a frequent change between the different tonal values of the partial areas. The partial areas differ in terms of their areal extent and / or their light / dark contrast and / or their tactility. The exact register between the different printed sub-areas and the associated special visual impression of the security print image can only be produced by intaglio printing, ie using a printing plate into which the security print image is completely engraved and with the necessary register. Advantageously, the predominant part of the ink-carrying partial areas directly adjoins one another, so that an essentially full-area printed image is present in the later printed image.

The intaglio printing plates according to the invention are preferably produced by engraving with a rapidly rotating, tapering stylus, such as, for example, using a method described in WO 97/48555. In principle, the engravings can also be produced by means of laser engraving or etching or any other suitable removal method.

In order to prevent immediately adjacent ink layers from flowing into one another along their boundary line after they have been transferred to a data carrier before the printing ink has dried, so-called “separating edges” according to WO 00/20216 and WO 00/20217. These separating edges have a tapering, wedge-shaped cross-sectional profile, and the tip of the wedge is preferably at or slightly below the surface of the printing plate. The tip of the separating edge profile forms a largely one-dimensional line along the separating edge, similar to a knife edge. Although it separates the printing plate areas of different engraving depths from each other, it does not produce an interruption of the printed color areas without printing inks. With the support of the separating edge integrated into the printing plate, the intaglio printing ink, which has a pasty consistency, remains "dimensionally stable" after it has been transferred to a substrate, even if areas printed with different layer thicknesses directly meet. In intaglio printing, the finest, superimposed structures with different color layer thickness and high edge sharpness can be printed.

If the engravings of the printing plate are not or at least partially not inked before the printing process, that is, not filled with printing ink, the non-inked area of the printing plate acts only as an embossing plate with which so-called blind embossing can be produced on a substrate during intaglio printing. With the exception of the visual impression created by the printing ink, the embossed elements have similar proportions and tactile properties to the previously described printed areas.

Finally, the data carrier is printed with the printing plate produced in this way.

Due to the high contact pressure, the substrate material is additionally embossed in intaglio printing, which is also apparent on the back of the substrate. The implementation of a halftone template in a print image according to the invention is preferably carried out as follows:

1. Determination of the number of tonal values with which the halftone template (e.g. a photo) is to be reproduced using printing technology.

It should be noted here again that the more tonal values are used, the closer you get to the appearance of the original. However, tests have shown that five or six tone values already enable sufficiently precise halftone reproduction.

2. Generation of the tone value excerpts from the halftone template.

3. Definition of the printing ink with which the halftone motif is to be reproduced by printing.

4. Determination of the transparency area of the printing ink (if not already done) and assignment of tonal values to ink layer thicknesses or engraving depths.

5. Definition of the partial surfaces of the printing plate to be created by defining the surface areas with a defined engraving depth, defining the separating edges, the ink trapping structures, etc.

6. Production of the printing plate by removing the respective layer areas, preferably by means of engraving technology according to WO 97/48555.

7. Print the test prints to evaluate the printing implementation and, if necessary, make corrections. In order to increase the stability of the data carrier, it can make sense to cover the halftone image according to the invention with a coating, such as a lacquer layer. This lacquer can contain feature substances such as luminescent substances etc. or other effect pigments such as liquid crystal pigments. In addition, the lacquer can be made matt or glossy. In addition, the protective lacquer layer also serves to enhance the gloss effect and protect the print.

All substrate materials suitable for intaglio printing, such as paper, plastic films, paper laminated or coated with plastic films and multilayer composite materials are suitable as substrates or data carrier materials. In particular, the method according to the invention is suitable for printing on data carriers which have to meet high requirements with regard to security against forgery, such as security and value documents, such as banknotes, shares, bonds, certificates, vouchers and the like.

Complex printed images in particular can be reproduced by the immediate and in any order adjoining of printed areas and areas with different ink layer thicknesses. This enormously increases the freedom of design when creating and reproducing print images created using the intaglio printing process.

The method according to the invention for producing corresponding printed data carriers also has considerable economic advantages, since the areas provided for printing with different ink layer thicknesses are produced in one printing pass using one and the same printing ink. The data carriers printed according to the invention have increased protection against forgery, since they cannot be reproduced with conventional printing methods due to the characteristic intaglio printing image. When two printed images, which are generated by successive, mutually independent printing or embossing processes, are superimposed, this register-accurate positioning of the partial areas relative to one another is not possible.

The tactilely perceptible image elements additionally offer effective protection against imitation by color photocopying or scanning the data carrier.

The intaglio printing technique, in particular the steel intaglio printing technique, provides a characteristic print or embossed image that is easy to recognize even for laypeople, which cannot be reproduced with other common printing processes. The steel intaglio printing technique is therefore preferably used for printing on data carriers, in particular security and value documents, such as banknotes, shares, bonds, certificates, vouchers and the like, which have to meet high requirements with regard to security against forgery.

The advantages of the invention are explained on the basis of the following examples and additional figures. The individual features described and the exemplary embodiments described below are inventive in themselves but also inventive in combination. The examples represent preferred embodiments, to which, however, the invention is not to be restricted in any way. The proportions shown in the figures do not necessarily correspond to the conditions in reality and serve primarily to improve clarity. Show it:

1 is a banknote in supervision,

2 is a halftone image template,

3 shows a halftone image template converted into tonal value extracts,

4 an inventive halftone image with partial areas,

5 a halftone image template, overlaid with a pixel grid,

5a shows a detail from FIG. 5,

5b is a plan view of a print image according to the invention,

6 a halftone image template converted into tonal value extracts, superimposed with a pixel grid,

6a shows a detail from FIG. 6,

6b is a plan view of a print image according to the invention,

7 shows a halftone image template, overlaid with partial areas related to tonal value,

8 a halftone image template converted into tonal value extracts, superimposed with a line screen, 8a shows a detail from FIG. 8,

8b is a plan view of a print image according to the invention,

9 is a halftone image template, overlaid with a line screen,

9a shows a detail from FIG. 9,

9b is a plan view of a print image according to the invention,

10 shows a further variant of a printed image according to the invention,

10a and 10b sections from FIG. 10 with fine structures,

11 shows a further variant of a print image according to the invention,

12 is a plan view of a print image according to the invention with additional tactile structural elements,

12a shows a cross section through a printing plate according to the invention,

12b shows a cross section through a data carrier according to the invention along A-A in FIG. 12,

13 and 14 cross sections through a printing plate according to the invention,

15 shows a cross section through a data according to the invention pinion carrier.

In Fig.l, a bank note is sketched as data carrier 1. The printed image of a banknote is typically a superimposition of several printed images, each of which is generated separately using different printing methods. The banknote shown shows, for example, a printed image 2 which represents the number 5. This printed image 2 is implemented in conventional engraving technique, which means that different brightnesses are reproduced by line screens with varying line spacing or line width. There is also a background pattern 3 of fine lines generated in offset printing and a serial number 4 applied in letterpress printing. Furthermore, partial areas could be provided that are created using screen printing technology, etc.

The imprint 5 according to the invention, which is intended to represent a portrait, is provided in a portion of the banknote in the example shown here and is only shown schematically. The exact description of the printed image according to the invention, of the printed data carrier and of the printing plate used is explained with the aid of the following examples and figures.

Fig. 2 shows a halftone image which is to serve as a template for the printed halftone image according to the invention. In the present case, it is a black-and-white photograph that usually does not have a raster that can be seen with the naked eye. The screening shown in FIG. 2 is chosen only in the alternative in order to make the “photo” reproducible in terms of printing technology. The image in FIG. 2 shows a section of a portrait and is to be understood as a classic halftone image, in which between the bright most tonal value, here white, and the darkest tonal value, here black, there are a large number of intermediate tones.

In the sense of the invention, halftone separations are created from the halftone template. 3 shows e.g. a halftone image template from tone value extracts with five tonal values, namely white, light gray, medium gray, dark gray and black, which were derived from the halftone image template as shown in FIG. 2. A grid can now be superimposed on these templates according to FIG. 2 or FIG. 3, with certain tonal values being assigned to the individual partial areas (pixels) resulting from the rastering.

The image template can be broken down into partial areas using any grid shape. Simple, regular geometric structures as well as statistically distributed, irregular and complicated structures can be used. The boundaries of the partial areas can be defined as well.

Among other things, parallel, almost parallel, spiral-shaped, star-shaped, intersecting or intertwined line systems with zigzag, wavy, curved, circular or straight lines, guilloches, geometric structures such as circles, ellipses, triangles and other polygons.

Of course, the various grid variants described for the decomposition of a printed image into partial areas can also be combined with one another. The image template can be divided into partial areas and is subject only to the restriction that printed partial areas adjoin one another in at least one partial area of the printed halftone image. The engraving depths for converting the template into an engraving on an intaglio printing plate are in turn assigned to the template image converted into partial areas with specific tonal values. The engraving depths depend on the printing ink and are essentially determined by the transparency bandwidth of the printing ink to be used.

Various embodiments of the invention are explained by way of example using the following examples.

example 1

If you want to get the most true-to-life image of the print template, it is a good idea to rasterize the area of the template image. This variant is shown in Fig.4. The partial areas 6, 7, 8, 9 and 10 are thus obtained from the image template itself. This means that the partial areas refer to a pictorial section in the template. This is done automatically when creating halftone separations, in which areas that correspond to a certain tonal value range are assigned to partial areas, which are then reproduced with a uniform tonal value. This leads to two-dimensional image templates in which the respective tonal values are subdivided into tonal value ranges and each tonal value range is represented by a defined tonal value. For example, with five tone value ranges, the total range of tone values 0 - 100% is divided into five equal parts, ie from 1 - 20%, from 21 - 40%, from 41 - 60% etc. Then each of the tone value ranges is divided by, for example, the highest The tonal value of the individual areas is summarized, ie the tonal values ranging from 1 - 20% are reproduced by a uniform tonal value of, for example, 20%, that of 21 - 40% by a tonal value of 40% etc. The tonal values of the mentioned games are thus 0%, 20%, 40%, 60%, 80% and 100%. The tone value ranges can also be selected irregularly, for example 0%, 30%, 60%, 80%, 90%, 100%. In this case, for example, the lighter areas of the image are rated less strongly than the dark areas of the image. It should also be noted that a tone value excerpt usually does not represent a coherent area, but consists of individual island-shaped areas that can be distributed over the entire image area, so that each of these island-shaped areas can be assigned a partial area according to the invention with the corresponding tone value. The partial areas belonging to a tone value extract are characterized by a uniform engraving depth or ink layer thickness in the overall printed image. In this case, the raster superimposed on the original is precisely adapted to the boundary lines of the areas that represent certain tonal values. If one looks at the image shown in FIG. 4, three black partial areas 6 would result, for example, which have the dimensions of the areas black in the template. Furthermore, the corresponding subareas for the dark (7), medium (8) and light gray (9) and white areas (10) were available. The dimensions of the partial areas and thus the later engraving result directly from the image areas in the template. Once the dimensions of the partial area and the tone value assigned to it and the associated engraving depth have been determined, all the necessary data for converting the image into an engraving are known.

The black dividing lines 11 shown in FIG. 4 are normally not visible in the printed image. They only serve to better illustrate the boundaries of the partial areas. In the area of these black lines in the printed image, the partial areas directly adjoin one another without being separated from one another by lines. When using a printing plate with the separating edge described above, which extends to just below the printing plate surface, there is in the area of the black lines shown in FIG. 4 in the printed image if necessary, to see a very fine, bright, but color-coated, ie printed line. The partial area 10 which appears white in the printed image, provided that there is a white substrate to be printed on, is an unprinted area in the otherwise fully printed image.

Example 2

In addition to the method described in Example 1 of determining the partial areas as a function of the image motif, it is also possible to align the template with a separately generated raster in order to generate the partial areas of the printed image. According to this embodiment, a raster will be placed over the original image, i.e. The original image is split up into partial areas, regardless of the motif. Tone values are assigned to these partial areas, which correspond to the partial areas in the print image according to the invention. In other words, the finer the grid, the smaller the partial areas from which the halftone image according to the invention is composed, the more image details can be captured. As described above, these tonal values are then converted into engraving depths for the printing plate.

In the simplest case, a pixel grid is used. In FIG. 5, the image template from FIG. 2 was overlaid with this grid. As a result, the original image is resolved into uniform square sub-areas 12. A partial area 12 is thus represented by a box / pixel. 5a shows a section from FIG. 5 with the section labeled "x". As explained in Example 1, the black lines in FIGS. 5 and 5a only serve to delimit the partial areas. They are not black lines in the printed image visible. In the next step, a certain tone value is assigned to each box or pixel. If there are several tonal values in one box, an average is formed, for example, via integration, which then determines the tonal value of the pixel. Since the classic halftone image according to FIG. 2 was used as the image template, this method results in a large number of tone values which are converted into corresponding engraving depths.

In contrast to the known gravure printing plates, the engraving areas according to the invention for the pixels are so closely adjacent that the separation takes place only via the separating edges described above. The dividing edges in the printing plate "physically" separate the individual pixels (wells), but in terms of printing technology they cause a direct transition from pixel to pixel despite the pasty printing ink. The pixels are therefore not separated by unprinted webs, at best by lighter printed lines. These lines are usually extremely fine, so that they do not stand out in the printed image. The image produced in this way is shown in FIG. 5b, the corresponding tonal values already being assigned to the individual boxes. The light lines in FIG 5b indicate how the separating edges are set when the printing plate is engraved and how the partial areas in the printed image are adjacent to one another They do not represent completely unprinted lines.

In order to ensure the clarity of the representation, the grid shown is kept relatively rough. The image, which is implemented over partial areas with certain tonal values, will therefore appear relatively abstract. If you want to create a more accurate image, you will of course choose a screen with a much smaller screen size, so that the pixels created are much smaller and less perceptible than individual boxes by the human eye. Example 3

The example illustrated in FIGS. 6, 6a and 6b, like example 2, is based on the use of a pixel grid. The difference, however, lies in the fact that not the classic halftone image from FIG. 2, but the halftone image from FIG. 3 made up of halftone extracts is superimposed on the raster.

As in example 2, a certain tone value is assigned to each individual pixel. Since the original is limited to five tonal values, the image converted into pixels also has only five tonal values, as shown in FIG. 6a. In other words, here the image is built up from a defined number of tonal values and the corresponding engraving depths.

Fig. 6 shows the halftone image overlaid with the pixel grid from five tone value excerpts. 6a shows the detail “x” indicated in FIG. 6, in which the tonal values have already been assigned to the pixels. FIG. 6b shows the print image associated with FIG. 6a, one pixel corresponding to a partial area 12.

The explanations under example 2 apply analogously here.

Example 4

As shown in FIG. 7, starting from the halftone separations according to FIG. 4, partial areas are again defined here that are generated from the image motif itself. These are represented by the black lines 11. The classic halftone image according to FIG. 2 is then superimposed on these partial areas. The individual partial areas can then be assigned specific tonal values which, in contrast to Example 1, are not limited to five tonal values, but can correspond to a large number of tonal values in the template. That is, the black areas 6, 6 'and 6 "are not, as in Example 1, implemented exclusively as black areas 6, but can be further differentiated by different dark gray to black tonal values. The same applies to the dark gray areas 7 and 7' and the medium-gray sub-areas 8 and 8 '. In addition, there is not only the possibility of assigning a specific tonal value to a sub-area, but also the possibility of displaying tonal value gradients within a partial area optionally equipped with dividers or paint traps, as explained for example 8 and FIG. 14.

Example 5

As shown in FIG. 8, as an alternative to the pixel grid, a line grid can also be used, with which the halftone template overlaid therewith according to FIG. 3 is divided into strips 13 which closely adjoin one another. In this variant, the image template is overlaid with horizontal parallel lines 11. In this case, however, a uniform tonal value is not assigned to each stripe, but the tonal value varies within a stripe in accordance with the tonal value extracts generated in step 2 if the tonal value extracts vary along the stripe. A partial area is thus delimited to the right and left and upwards and downwards by dividing lines 11 or, in the case of the printing plate, by dividing edges. The delimitation to the left and right results from the image motif and runs along the areas that have a certain tonal value, the dividing lines up and down result from the overlaid line grid. Partial areas that do not fill a line over their entire width are either averaged over the line width and then assigned to the respective tonal values according to the mean value, or, as shown, they are delimited within the strip with dividing lines.

FIG. 8a shows the section labeled "x" in FIG. 8, in which three strips 13 are identified by way of example. FIG. 8b shows the printed image belonging to the section "x".

The light borders of the partial areas in FIG. 8b again serve to illustrate the exact dimensions of the partial areas and indicate the use of separating edges in the printing plate.

The stripes and the areas within the stripes to which different tonal values have been assigned are separated from one another by means of separating edges. If the lines of the line grid run transversely to the wiping direction of the wiping cylinder / squeegee, this subdivision should already be sufficient. If the line grid runs along the wiping direction, longer partial areas within the stripes that are assigned a tonal value may need to be interrupted with further separating edges in order to avoid "splashing out" of the color during the printing process. The separating edges may produce thin, If this is to be avoided, the so-called “ink-catcher elements”, as described in Examples 8 and 14, can also be provided within the raster lines in the area of the printing plate surface. These do not protrude to the surface of the printing plate and appear less strongly in the later print image than the separating edges. Example 6

The variant shown in FIG. 9 differs from the embodiment described in Example 5 and FIGS. 8 to 8b in that it is not a picture based on halftone separations according to FIG. 3 that is overlaid with the classic halftone picture according to FIG , As in Example 5, the partial areas are delimited from one another by the individual lines 11 upwards and downwards, it being possible for any number of tonal values, as clearly visible in FIG. 9a, to be present in the individual lines. In terms of printing technology, the tone value curve within a stripe is realized by means of a printing plate in which oblique planes are engraved within a stripe, which is in turn delimited by separating edges to the next stripe. Due to the inclined plane in the printing plate, a continuously increasing or decreasing ink layer thickness is generated on the data carrier, which an observer perceives as a continuously lighter or darker tone value. As described in Example 5, separating edges are also recommended within the individual strips. In addition, there is the possibility of engraving color capture structures to prevent bleeding or splashing between the tonal value areas and lines. The light lines in FIG. 9b show the partial areas delimited from one another by separating edges in the printed image.

Example 7

10 shows a variant in which the partial areas are defined by the free graphic design of the image template. The image according to the invention is determined not by the arithmetically determined tone value excerpts from the photographic template, but by the creative division of the template into partial areas. Creative means such as shades, colors, etc. implemented using tonal values and partial areas. FIG. 10 shows the portrait section shown in FIG. 2 in a stylized form, four tone values being used, namely white (10), light gray (9), dark gray (7) and black (6).

Example 8

In contrast to the eyebrow "y" shown in FIG. 10, which in the simplest printed image variant presents itself as a structureless black surface, FIGS. 10a and 10b show different embodiments of the eyebrow "y" which are equipped with motif-dependent fine structures. Therefore, not only a depression corresponding to the eyebrow, but also an additional roughness pattern is engraved in the associated printing plate, which creates the desired fine structures in the printed image.

Due to the shape and the guidance of the engraving tool, this roughness pattern can be created on the base of the partial areas created by the engraving, which pattern serves as a color catcher for the printing ink and influences the gloss and the visual impression of the printed or embossed image parts. The basic roughness pattern is produced, for example, in accordance with the method described in WO 97/48555 when the printing plate is engraved on the bottom of the cleared areas. With dimensions of the partial areas from a length and width of about 100 μm, for example, a color catch is expedient. Engraving tools with a large tip radius and round geometry and closely spaced clearing paths (for example approx. 10 μm) achieve smooth engravings that produce smooth and generally reflective printing surfaces or embossing. On the other hand, if you choose a small tip radius for the engraving tool with a pointed cutting edge geometry and more distant clearing paths (for example roughly 50 μm), you get rough, structured engravings that produce a matt and diffusely scattering printing surface or embossing.

On the one hand, the roughness pattern can be carried out uniformly in the entire printed image, but there is also the possibility of changing the clearing direction in individual partial areas when engraving the depressions in the printing or embossing plate. Engraving that has been engraved along linear, but for example, clearing paths rotated by 90 ° produce visually distinguishable printing areas or embossing with different light reflection. The same applies to engravings with straight or meandering clearing paths in comparison to spiral or concentric clearing paths. These effects can not only be used to make the embossing or printing more appealing or eye-catching, but at the same time also increase their security against counterfeiting. With the help of this specifically used engraving technique, fine structures can be superimposed on the printed or embossed area, e.g. support the image information graphically, but they are only clearly recognizable under certain viewing or reflection angles or when viewed with a magnifying glass.

If one selects the fine structures mentioned, as shown in FIGS. 10a and 10b, the type of engraving of the plate can also be used to effect the eyebrow hair in the form of a fine structure in the area of the eyebrow, for example. In FIG. 10a, the engraving tool was guided concentrically along the contours of the partial surface to be cleared, while in FIG. 10b the engraving tool was guided on parallel lines. Other structures, such as oblique hatching, cross grids, etc. are also possible. Example 9

11 shows a halftone image according to the invention which, as in Example 7, has freely designed, motif-dependent partial areas. The sub-areas are assigned four different tonal values. The difference to Example 7 is that this is not a portrait display, but rather the implementation of graphic and alphanumeric elements, with the individual elements each representing a partial area. The explanations for example 7 apply analogously.

Example 10

As explained at the beginning, the halftone image according to the invention already has a certain tactility due to the different color layer thicknesses and embossing of the paper substrate in the range of different tonal values. If the tactility in the printed image according to the invention is to be further enhanced, this can be done e.g. print image generated according to Examples 1 to 9 can be equipped with additional tactile structures. These structures are taken into account in the engraving of the intaglio printing plate, so that even with this variant only one printing process is necessary. The size of the structural elements, their tonal value and their arrangement must be considered for each individual case and aligned with the desired tactile and visual effects.

12 schematically shows a print image 20 according to the invention, which consists of a gray wedge and additional tactile structural elements. The gray wedge has four squares 21, 22, 23, 24 with four different tonal values. Each square has an edge length of 5 mm, for example, and corresponds to a partial area. This "halftone image" is already tactile perceptible due to the relief structure of the printed image. Since the gray values run continuously from "dark" to "light", the beginning of the gray wedge, ie the black edge, can be detected tactilely. However, the further levels are there declining and changing only in small steps, less noticeable In the basic motif, smaller black circles 25, 26, 27, 28 are now worked into the squares as additional tactile structural elements. The additional structural elements are engraved much deeper than it is for the representation of the tonal value "Black" would be necessary. They therefore have a higher relief amplitude than the black partial area 21 of the gray wedge. The structural elements 25 to 28 are thus a kind of "knobs" in the square partial areas. "Knobs" and partial areas are delimited in the printing plate by separating edges and appear in register in the printed image. They can be felt in all areas, even in the black, from all directions, regardless of the contrast or the gray gradient. The element 25 optically has the same tone value as the square 21, but is only tactile, not visually perceptible. Of course, not only circles but also other elements such as squares, letters etc. can be used as additional tactile structural elements. The individual elements can be arranged in any way in the basic motif. In the present case, a tactile structural element is centered in each partial area. However, a tactile structural element can only be present in every second or third square. The structural elements can vary not only in shape, but also in size. They can also have different tonal values.

In a further embodiment, for example, the partial areas described in example 1 and FIG. 4 can be specifically delimited from one another by means of borders which are tactile and possibly also visible in the printed image. The black and invisible described in Example 1 and Fig. 4 In this variant, the lines are made tactile and visually perceptible. These are preferably lines with very dark tonal values, particularly preferably in black. This has the advantage that these lines can be perceived relatively easily in a tactile manner in the printed image and can be used in the sense of the additional tactile structural elements. The lines themselves can vary in thickness, for example, and can only be used in a partial area of the picture motif.

The tactility is advantageously increased by means of structural elements which have a darker tone value than the adjacent partial area, since a darker tone value also means a greater amplitude, which is composed of the ink layer thickness and embossing, and can thus be perceived easily in a tactile manner. Lighter tonal values are also conceivable. In this case, the tactility has a positive effect if the structure elements with the lighter tonal values are not chosen too small, since these are usually less embossed and therefore more difficult to detect tactile than structure elements protruding from the printed image surface. In the present example, the tactile structural elements are partly only tactile and partly tactile and at the same time visually perceptible. A tactile structural element 25 is incorporated into the first basic square 21. Here, both the structural element and the basic square have the tone value black, the structural element being produced with a deeper engraving and thus having a higher amplitude than the basic square. The structure element and the base square have different layers of the color layer, the layer thicknesses being chosen so large that the color is no longer translucent, and thus the structure element and the base square have the same tonal value when viewed from above and are not visually distinguishable. Depending on the training, the tactile elements can still be in the glancing angle due to different shadows be visible, even if under supervision they are indistinguishable from the surface. In this case, the tactile structural elements can be used to introduce information which is visible in the gloss angle and which can serve as an additional authenticity feature. If you want an additional tactile structure that should not be visible, you have to choose structural elements that have the same tonal value as their surroundings, but that have a noticeably distinguishable relief.

Since tactile perception is a subjective sensation, a value from which a relief is perceived tactilely can only be determined within broad limits. In addition to the absolute relief height and individual sensitivity, the tactile perceptibility of a printed image relief also depends on the areal extent of the printed structure and whether the printed structure to be felt is free-standing or integrated into a relief-like environment.

As a rough guideline, however, the following information can be given. A print relief created in intaglio printing can be felt tactile below a relief height of approx. 50 μm. Relief areas between approx. 50 μm and 60 μm can be felt well. With relief amplitudes greater than 60 μm, the intaglio relief can be clearly felt.

FIG. 12a shows an intaglio printing plate 30 according to the invention, with which a print image, as shown in FIG. 12 along the section line AA, is generated. The engraving areas 31, 32, 33 and 34 each correspond to a square with an integrated tactile structural element. The respective squares as well as the structural elements are delimited from one another with the aid of separating edges 39 which do not extend to the printing plate surface. In the area 34, an additional color catch is incorporated, which is shown as a zigzag pattern and which creates a surface texture in square 24 (see FIG. 12b).

FIG. 12b shows in cross section a data carrier 40 with the print image shown in FIG. 12 along the section line A-A. The substrate 50 has embossments of different thicknesses on the paper substrate and color layers depending on the engraving depth in the printing plate. In the area of the black basic square 21 there is a very strong embossing with a thicker color application 41. Both the embossing and the color application 42, 43, 44 decrease for the squares 22, 23, 24 which are lighter in tone value and to the right of it. The additional tactile structural elements 25, 26, 27, 28 can be recognized as bumps of different heights.

It should be noted that a relief on the data carrier surface does not match the engraving depth of the printing plate identically. The surface relief shown in FIG. 12b is idealized. The surface relief created by the printing is composed of a compression of the substrate material and the application of the color layer. The total height of the relief is based on the normal, ie unprinted and unprinted, data carrier surface. In practice, the relief created on the substrate and the engraving in the printing plate are very different. The reason for the deviations between the engraving depth and the relief height is due to the fact that the data carrier is not pressed into the bottom of the printing plate engraving during the printing process and the color present in the depressions of the printing plate is also not completely transferred to the data carrier. Accordingly, the engraving depth of the printing plate for relief-like structures is in the range from approx. 40 μm to 250 μm, preferably in the range from approx. 55 μm to 150 μm. They produce relief structures in the range from approx. 5 μm to 100 μm, preferably 25 to 80 mμ. Whether an engraving depth in the border area on the surface of a data carrier leads to a relief-like or rather flat imprint also depends in individual cases on the steepness of the edge of the engraving, the nature of the substrate to be printed (strength, plastic deformability) and the color properties.

Since, as already mentioned, the relief height achieved in the printing result depends not only on the engraving depth of the printing plate, but also on the properties of the substrate and the printing ink, in extreme cases an engraving depth of 40 μm can lead to a relief-like print image, while at other material and printing parameters, an engraving depth of 50 μm can still lead to a flat print image. In each specific application, however, the engravings leading to relief-like printed image areas are always deeper than those that produce so-called flat, tactile, imperceptible image areas.

Example 11

In the following FIGS. 13 to 15, printing plates and printed data carriers according to the invention are described by way of example. The statements on this, in particular general descriptions of the inventive concept, are of course not limited to these special variants.

FIGS. 13 to 15 schematically show excerpts from an engraved surface of an intaglio printing plate 60 according to the invention, with which a print image according to FIG. 4 could be generated. Indentation 61 in the printing plate has a very large engraving depth and produces a section, for example shown in black, in the printed image. Right next to it detached, with a separating edge 39, is an engraving area 62 with a smaller engraving depth, which appears in the printed image, for example, light gray. Following the light-gray partial area is a medium-gray partial area, which corresponds to the engraving area 63 in the printing plate. The adjoining dark gray area corresponds to a wide and again more deeply engraved area 64 in the printing plate. After an area 65 producing the tonal value middle gray, the engraving area is closed off with a surface 66 appearing light gray in the printed image. All engraving areas 61 to 66 are delimited from one another by separating edges 39. The printing plate shown in FIG. 14 corresponds to the printing plate shown in FIG. 13 with the difference that the area 66 was additionally equipped with an ink catcher due to its width, which is indicated at the bottom of the engraving with a zigzag pattern.

The printed data carrier 70 associated with these printing plates is shown in FIG

Fig. 15 shown in cross section. The substrate 50, here banknote paper, is printed with glazing intaglio printing ink and deformed accordingly by the printing process. As explained above, deep engravings in the printing plate produce strongly embossed areas with a large amount of ink, while less deeply engraved areas emboss less, ie deform less, and in these areas less color is transferred from the printing plate to the data carrier , The area labeled 61 in FIG. 13 corresponds to area 71 in FIG. 16. The strong embossing and a thick application of paint can be clearly seen. The indentation 79 lying to the right was created by the separating edge 39. The light gray printing area 72 with less ink application than in the area 71 seamlessly adjoins the black area 71 in the printed image despite the separating edge. The areas 73 and 75 which appear medium gray are in turn printed and embossed more strongly. Significantly more embossed and with a thicker The area 74 appears dark gray in the printed image. The area 76 is only slightly embossed and due to the thin ink layer thickness it appears light gray in the printed image. The printed image surface shows a distinctive relief structure in the area shown, which is composed of the embossing and the application of color. This relief structure is easily palpable even for the layperson and is a clearly identifiable safety criterion.

Claims

Patent claims

1. Data carrier (1) with at least one halftone image produced by intaglio printing, which comprises printed partial areas directly adjacent to one another in at least one partial area of the image, characterized in that the partial areas have specific tonal values and at least one partial area of the image is tactile perceptible.

2. Data carrier according to claim 1, characterized in that there are at least three different tonal values.

3. Data carrier according to claim 1 or 2, characterized in that the halftone reproduces a portrait.

4. Data carrier according to at least one of the preceding claims, characterized in that the partial areas are derived from a raster superimposed on the halftone image template.

5. Data carrier according to at least one of the preceding claims, characterized in that the grid is a pixel grid.

6. Data carrier according to at least one of the preceding claims, characterized in that the raster is derived from image information of the halftone image template.

Data carrier according to at least one of the preceding claims, characterized in that the partial surfaces are tactile.

8. Data carrier according to at least one of the preceding claims, characterized in that the halftone image has additional tactile structural elements.

9. Data carrier according to at least one of the preceding claims, characterized in that in each case a tactile structural element is arranged in a partial area.

10. Data carrier according to at least one of the preceding claims, characterized in that the tactile structural element has a larger or smaller amplitude compared to the partial area.

11. Data carrier according to at least one of the preceding claims, characterized in that the tactile structural element is not visually perceptible.

12. Data carrier according to at least one of the preceding claims, characterized in that at least a part of the partial surfaces is equipped with a roughness pattern which brings about a visually distinguishable light reflection.

13. A data carrier according to at least one of the preceding claims, characterized in that fine structures are superimposed on the halftone image, at least in partial areas, which influence its visual appearance and which have different orientations in individual partial areas.

14. Data carrier printed with the printing plate according to claims 16 to 18.

15. A method for producing a data medium with a halftone image, comprising the following steps:

a) provision of a data carrier material,

b) producing an intaglio printing plate according to at least one of claims 16 to 18 and

c) printing on the data carrier material with the intaglio printing plate produced in step b).

16. Intaglio printing plate for printing a halftone image with at least one engraved area in the printing plate surface, characterized in that the engraved area, at least in a partial area, directly adjoins partial areas with a certain area

Has engraving depth.

17. Intaglio printing plate according to at least one of the preceding claims, characterized in that the partial surfaces have the same and / or different engraving depths.

18. Intaglio printing plate according to at least one of the preceding claims, characterized in that partial areas with at least three different engraving depths are present.

19. A method for producing an intaglio printing plate according to at least one of claims 16 to 18, comprising the following steps,

a) converting a halftone image template into partial areas, b) assigning certain tonal values to the individual partial areas,

c) assigning certain engraving depths to the tonal values and

d) Engraving the partial areas with the assigned engraving depth in the

Printing plate surface.