EP1459268B9 - Valuable document - Google Patents

Description

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

Data carriers in the sense of the invention are security or value documents, such as banknotes, identity cards, passports, check forms, shares, certificates, stamps, air tickets and the like, as well as labels, seals, packaging or other elements for product assurance. 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 identifiable by appropriate measures as genuine and distinguishable from counterfeiting and counterfeiting. They are therefore provided with special security elements that are ideally not or only with great effort imitable and not falsified.

In the past, especially those security elements have proven to be identified by the viewer without aids and recognized as genuine, but can be produced at the same time only with great effort. These are, for example, watermarks which can only be introduced into the data carrier during papermaking, or designs produced by intaglio printing, which are distinguished by their characteristic tactility that can not be copied by copying machines.

The line or intaglio printing technique, in particular the Stahlstichtiefdrucktechnik is for the printing of data carriers, in particular of securities, such as banknotes and the like, an important technique.

The intaglio printing is characterized by the fact that linear depressions are introduced into 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 by means of a suitable engraving tool or by etching. In the case of the mechanically produced printing plate for intaglio printing, a wider line is produced with increasing stitch depth due to the usually tapered engraving tools. In addition, the ink receptivity of the engraved line, and hence the opacity of the printed line, increases with increasing stitch depth.

During the etching of intaglio printing plates, the non-printing areas of the printing plate are covered with a chemically inert lacquer. By subsequent etching, the engraving is produced in the exposed plate surface, the depth of the engraving lines depending in particular on the etching time. Prior to the actual printing process, pasty consistency is applied to the engraved printing plate and the excess printing ink is removed from the surface of the printing plate by means of a doctor blade or a wiping cylinder so that the ink remains only in the depressions. Subsequently, a substrate, usually paper, pressed against the printing plate and thereby also in the filled with ink wells of the printing plate and withdrawn, the color is pulled out of the wells of the printing plate, adhering to the substrate surface and forms a printed image , If translucent colors are used, the thickness of the paint application determines the color tone. That's how you get When printing on a white medium with low ink layer thicknesses, a light tint, when printing with thick ink layers darker hues. The ink layer thickness is in turn dependent to some extent on the engraving depth.

Line intaglio printing technology allows a relatively thick application of ink on a data carrier in comparison to other common printing techniques, such as offset printing. The comparatively thick ink layer produced in the line intaglio printing process, together with the partial deformation of the paper surface, which comes about when the paper is pressed into the engraving of the printing plate, can easily be felt manually even by the layman and can thus easily be recognized as an authenticity feature by virtue of its tactility. The tactility is not imitated with a copier, so that the Linichtichtiefdrucktechnik provides high-quality protection against counterfeiting.

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

From engraving or line gravure we distinguish another gravure printing technique, namely the gravure printing. Characteristic of the rotogravure printing, in particular for the autotypical engraved gravure printing is that different gray or color values of the printed image are generated by regularly arranged in the pressure plate with wide webs spaced wells of different density, size and / or depth. In the rotogravure method The production of printing plates, for example, mechanically by means of Stichelwerkzeugen or by ablation using electron beam or laser beam. Typical for gravure printing is the use of low-viscosity paint and a squeegee. The principle of the printing process is based on filling the wells with the low-viscosity ink and keeping the ink in the different deep wells. The screen webs that delimit the cups serve as a support for the squeegee, but are not self-printing. During printing, however, the boundaries between the adjacent pressure surfaces are due to the thin liquid of the color, so that they are no longer exactly separable. It results almost a full-surface print. 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 can not be achieved in one print run with simultaneous full-surface printing in the printed image.

The object of the present invention is to provide a security or value document with increased security against counterfeiting, which has both a tactile and a printing technology difficult to imitate and visually striking, as generated in intaglio, spatially represented image motif.

A further object is to provide a printing plate for producing the document printed according to the invention as well as a corresponding production method.

This object is solved by the independent claims. Further developments are the subject of the dependent claims.

The invention is based on the fact that the print image provided on the data carrier and produced in intaglio printing represents a halftone image. This halftone image comprises in at least a partial region of the image directly adjacent printed partial areas, each of which has a specific tone value, wherein at least three of the printed partial areas differ from one another by their specific tone value and at least a partial area of the image is tactile perceptible.

"Halftone image" in the context of the invention refers to an image which has intermediate tones between the brightest and darkest image location. If it is a black-and-white image, "tonal value" is, as usual, a value on a gray scale from white to black. However, the present invention relates not only to black-and-white halftone images containing the achromatic colors, namely white, black and gray, but of course also monochrome or multicolor halftone images comprising the so-called bright colors. In the case of the colorful halftone images, the term "tone value" is understood to mean the brightness of the color under consideration. The image according to the invention comprises at least three printed tonal values. If the base color of the substrate to be printed, for example the white of the paper, is integrated into the design of the image, the image has four tonal values, for example white, black and two gray values. In particularly preferred embodiments, the printed image on a much larger tonal range, so that in addition to light and shadow effects and plastic effects can be achieved. The finer the tonal gradations, ie the larger the tonal scale, the better motives can be spatially represented and ideally the printed image approaches a photographic representation, whereby the tonal gradations merge into each other almost continuously. Experiments have shown, however, that even four halftone levels give a very realistic halftone impression. Even with six halftone levels, the difference to the photographic halftone image is only relatively small for the layman.

The halftone image can represent any motif. However, preferred are pictorial representations. However, particularly preferred is the representation of portraits, since the human perception is trained on the finest differences in portraits and thus the recognition value and thus the security value of this security element is particularly large. You can also combine multiple halftone images in any number and shape.

Since conventional intaglio inks are somewhat translucent and translucent, color or gray tones of different brightness and color saturation result with suitable layer thicknesses and sensible choice of the color of the substrate. 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, i. the printed areas of different tonal values are printed with a different thickness of color layer. Thus, when printing on a white data carrier with low ink layer thicknesses, light color tones are obtained, while when printing with thick color layers, darker color tones are obtained. It is also not excluded that depending on the ink used and substrate depending on the layer thickness in addition to the brightness and the color saturation can change. Usually, however, the color layer thickness mainly affects the brightness value and the saturation. The influence of the layer thickness on saturation and brightness is in each individual case, i. for each color and each substrate, to be determined accordingly. If there is sufficient difference in the ink layer thicknesses of adjacent areas, the human eye will see well visible contrasts without any further aids. Normal lighting conditions and a normal viewing distance are assumed.

To produce a printed image according to the invention, first a template, preferably a portrait, is subdivided into halftone-value-related partial surfaces. The individual tonal values or groups of tonal values of this conversion are then assigned different engraving depths for the printing plate to be produced, matched to the printing ink used. For example, maximum engraving depth for black and minimum engraving depth or unsigned 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 necessary for the production of a specific tone value varies from printing ink to printing ink.

Which assignment is necessary, can be easily determined by a stepped gray wedge is printed with the printing ink under discussion. For this purpose, the gray wedge has a large number of surface elements which are arranged next to one another and differ in defined steps of engraving depth. If, for example, the engraving depth is varied in increments of 5 μm, the gray scale begins with a field with a 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, for example, 100 μm. The field size is for example 5 x 5 mm. The individual fields are only separated by narrow separating edges.

If you now print the gray wedge with a special color, you will see that the first field has a special bright tonal value, which is in contrast to the next field, with the next fields each having darker tonal values up to a field with the darkest tonal value is present. There is no tonal variation from this field. 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 that are needed for the production of the printing plate.

For each ink, this gray wedge test is to be created separately. If an ink has too low a "transparency bandwidth", i. too few contrasting with increasing engraving depth tonal values, this can be adjusted by the skilled person known measures.

If one prints a halftone image in which the engraving depths of the tonal ranges are matched to the transparency of the printing ink, one obtains a halftone resolution without the otherwise usual raster 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 formed higher than the bright.

"Partial surfaces" in the sense of the invention designate surfaces which make up the halftone image. The partial areas are printed and optionally unprinted areas, with at least a portion of the printed partial areas directly adjoining each other. "Directly adjacent" means that in the printed image the adjoining partial surfaces are not separated by unprinted areas. Preferably, the proportion of the printed partial areas in the continuous tone image printed according to the invention is greater than the proportion of the unprinted partial areas. Furthermore, the printed partial areas are preferably predominantly adjacent to one another, so that the impression of a substantially full-surface printing arises in the continuous tone image printed according to the invention. The adjoining partial surfaces can have different tonal values, ie different color layer thicknesses, but also identical tone values, ie the same color layer thickness. In particular, unprinted areas are mainly used for design purposes, for example, to represent light reflections or highlights.

The security against forgery of the security element or security print image according to the invention can finally be further increased by a frequent change takes place between the different tonal values of the partial surfaces. The faces 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 optical impression of the security printed image can only in the intaglio printing, i. using a printing plate in which the security print image is engraved completely and with the required register. Advantageously, the vast majority of the ink-carrying partial surfaces directly adjoin one another, so that in the later printed image there is a substantially full-surface printed image.

The intaglio printing plates according to the invention are preferably by engraving with a fast-rotating, tapered stylus, such as one in the WO 97/48555 described method. 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 directly adjacent color layers, after they have been transferred to a data carrier, to flow into one another along their boundary line before the ink has dried, so-called "separating edges" are introduced into the printing plate between surfaces having different engraving depths WO 00/20216 and WO 00/20217 integrated. These dividing edges have a tapered, wedge-shaped cross-sectional profile. The tip of the wedge is preferably at the level of the printing plate surface or slightly below.

The tip of the separating edge profile forms along the separating edge a largely one-dimensional line, similar to a knife edge. Although it separates the printing plate areas of different engraving depths from each other, but creates no ink-free interruption of the printed color areas. With the support of the separating edge integrated in the printing plate, the intaglio printing ink, which has a pasty consistency, also remains dimensionally stable after it has been transferred to a substrate when surfaces printed with different layer thickness directly abut one another. In this way, the finest intaglio, superimposed structures with different color layer thickness and high edge sharpness can be printed in intaglio.

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

With the printing plate produced in this way, the disk is finally printed.

Due to the high contact pressure, the substrate material additionally undergoes embossing during intaglio printing, which is also evident on the back side of the substrate.

• 1. Festlegung der Zahl von Tonwerten, mit denen die Halbtonvorlage (z.B. ein Foto) drucktechnisch wiedergegeben werden soll.
  Hier ist nochmals anzumerken, je mehr Tonwerte Anwendung finden, umso näher kommt man an das Aussehen des Originals heran. Versuche haben aber gezeigt, dass bereits fünf ober sechs Tonwerte eine ausreichend präzise Halbtonwiedergabe ermöglichen.
• 2. Erzeugung der Tonwertauszüge aus der Halbtonvorlage.
• 3. Festlegung der Druckfarbe, mit der das Halbtonmotiv drucktechnisch wiedergegeben werden soll.
• 4. Ermittlung des Transparenzbereiches der Druckfarbe (falls nicht bereits geschehen) und Zuordnung von Tonwerten zu Farbschichtdicken bzw. Gravurtiefen.
• 5. Definition der Teilflächen der zu erstellenden Druckplatte durch Festlegung der Flächenbereiche mit definierter Gravurtiefe, Festlegung der Trennkanten, der Farbfangstrukturen etc.
• 6. Herstellung der Druckplatte durch Abtragen der jeweiligen Schichtbereiche,vorzugsweise mittels Gravurtechnik gemäß WO 97/48555 .
• 7. Andrucken der Probedrucke zur Bewertung der drucktechnischen Umsetzung und gegebenenfalls Vornahme von Korrekturen.

Preferably, in the implementation of a halftone original in a printed image according to the invention, the procedure is as follows:

• 1. Definition of the number of tonal values with which the halftone original (eg a photo) is to be reproduced by printing.
  It should be noted again that the more tonal values are used, the closer one gets to the appearance of the original. Experiments have shown, however, that even five upper six tonal values allow sufficiently accurate halftone reproduction.
• 2. Generation of Tonwertauszüge from Halftone Template.
• 3. Determination of the ink with which the halftone motif is to be reproduced by printing.
• 4. Determination of the transparency range 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 definition of the surface regions with a defined engraving depth, definition of the separating edges, the ink-catching structures, etc.
• 6. Production of the printing plate by removing the respective layer areas, preferably by means of engraving technique according to WO 97/48555 ,
• 7. proofing of the proofs for the evaluation of the printing technology implementation and if necessary making corrections.

In order to increase the stability of the data carrier, it may be useful to use the halftone image according to the invention with a coating, such as e.g. to cover a paint layer. This lacquer may contain feature substances such as luminescent substances etc. or other effect pigments such as liquid crystal pigments. In addition, the paint can be made matt or glossy. Furthermore, the protective lacquer layer also enhances the gloss effect and protects the print.

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

Even complex print images can be reproduced by the immediate and in any order contiguous printed areas and areas with different color layer thickness. The freedom of design in the creation and reproduction of printed images produced by the intaglio printing method is thereby increased enormously.

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 single printing pass with one and the same printing ink.

The inventively printed data carriers have an increased protection against counterfeiting, since they are not reproducible due to the characteristic intaglio image with common printing processes. When superimposing two printed images, which are produced by successive, mutually independent printing or embossing processes, this register-accurate positioning of the partial surfaces to each other is not possible.

The tactile perceptible picture elements additionally offer an effective protection against imitation by color photocopying or scanning the data carrier.

The intaglio printing technique, in particular the steel intaglio technique, thus provides a characteristic printing or embossing image, which is easily recognizable even to laymen, and which can not be readjusted with other common printing processes. The Stahlstichtiefdrucktechnik is therefore preferred for the printing of data carriers, in particular security and value documents, such as banknotes, stocks, bonds, certificates, vouchers and the like, which must meet high requirements regarding the security against forgery used.

The advantages of the invention will be explained with reference to the following examples and additional figures. The described individual features and embodiments described below are inventive in their own right but also in combination in an inventive manner. The examples represent preferred embodiments, to which, however, the invention should not be limited in any way. The proportions shown in the figures do not necessarily correspond to the conditions existing in reality and serve primarily to improve the clarity.

Fig. 1

eine Banknote in Aufsicht,

Fig. 2

eine Halbtonbildvorlage,

Fig. 3

eine in Tonwertauszüge umgesetzte Halbtonbildvorlage,

Fig. 4

ein erfindungsgemäßes Halbtonbild mit Teilflächen,

Fig. 5

eine Halbtonbildvorlage, überlagert mit Pixelraster,

Fig. 5a

einen Ausschnitt aus Fig. 5,

Fig. 5b

eine Aufsicht auf ein erfindungsgemäßes Druckbild,

Fig. 6

eine in Tonwertauszüge umgesetzte Halbtonbildvorlage, überlagert mit Pixelraster,

Fig. 6a

eine Ausschnitt aus Fig. 6,

Fig. 6b

eine Aufsicht auf ein erfindungsgemäßes Druckbild,

Fig. 7

eine Halbtonbildvorlage, überlagert mit tonwertbezogenen Teilflächen,

Fig. 8

eine in Tonwertauszüge umgesetzte Halbtonbildvorlage, überlagert mit Linienraster,

Fig. 8a

einen Ausschnitt aus Fig. 8,

Fig. 8b

eine Aufsicht auf ein erfindungsgemäßes Druckbild,

Fig. 9

eine Halbtonbildvorlage, überlagert mit Linienraster,

Fig. 9a

einen Ausschnitt aus Fig. 9,

Fig. 9b

eine Aufsicht auf ein erfindungsgemäßes Druckbild,

Fig. 10

eine weitere Variante eines erfindungsgemäßen Druckbildes,

Fig. 10a und 10b

Ausschnitte aus Fig. 10 mit Feinstrukturen,

Fig. 11

eine Aufsicht auf ein erfindungsgemäßes Druckbild mit zusätzlichen taktilen Strukturelementen,

Fig. 11a

einen Querschnitt durch eine erfindungsgemäße Druckplatte,

Fig. 11b

einen Querschnitt durch einen erfindungsgemäßen Datenträger entlang A-A in Fig. 11,

Fig. 12 und 13

Querschnitte durch eine erfindungsgemäße Druckplatte,

Fig. 14

einen Querschnitt durch einen erfindungsgemäßen Datenträger.

Show it:

Fig. 1

a banknote in supervision,

Fig. 2

a halftone original,

Fig. 3

a halftone image template converted into tonal separations,

Fig. 4

an inventive halftone image with partial surfaces,

Fig. 5

a halftone image overlaid with pixel grid,

Fig. 5a

a section from Fig. 5 .

Fig. 5b

a plan view of an inventive printed image,

Fig. 6

a halftone image template converted into tonal separations, overlaid with a pixel grid,

Fig. 6a

a cutout Fig. 6 .

Fig. 6b

a plan view of an inventive printed image,

Fig. 7

a halftone image overlaid with tonal subfaces,

Fig. 8

a halftone image template converted into tonal separations, overlaid with a line grid,

Fig. 8a

a section from Fig. 8 .

Fig. 8b

a plan view of an inventive printed image,

Fig. 9

a halftone image overlaid with line grid,

Fig. 9a

a section from Fig. 9 .

Fig. 9b

a plan view of an inventive printed image,

Fig. 10

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

10a and 10b

Cutouts off Fig. 10 with fine structures,

Fig. 11

a plan view of an inventive printed image with additional tactile structural elements,

Fig. 11a

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

Fig. 11b

a cross section through a data carrier according to the invention along AA in Fig. 11 .

FIGS. 12 and 13

Cross sections through a printing plate according to the invention,

Fig. 14

a cross section through a data carrier according to the invention.

In Fig.1 is sketched as a disk 1 a banknote. The printed image of a banknote is typically a superimposition of a plurality of printed images, each of which is produced by itself with different printing methods. The banknote shown shows, for example, a printed image 2, which represents the number 5. This printed image 2 is converted by conventional intaglio printing technology, which means that different brightnesses are represented by line rasters with varying line spacing or varying line width. Furthermore, a background pattern 3 of fine lines and a serial number 4 applied by letterpress printing are provided in offset printing. Furthermore, it would also be possible to provide partial regions which are produced in screen printing technology, etc.

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

Fig. 2 shows a halftone image 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 which usually does not have a pattern that can be recognized by the naked eye. In the Fig. 2 visible rasterization is only chosen as an alternative to make the "photo" printable duplicable. The picture template of Fig. 2 shows a section of a portrait and is to be understood as a classic halftone image, in which between the brightest Tonal, here white, and the darkest tone, here black, a multitude of intermediate tones are present.

In accordance with the invention, halftone separations are created from the halftone original. Fig. 3 For example, Fig. 12 shows a halftone image template of tonal separations having five tonal values, namely white, light gray, middle gray, dark gray, and black, taken from the halftone image template as in Figs Fig. 2 shown were derived. According to these templates Fig. 2 respectively. Fig. 3 Now, a raster can be superimposed, wherein the individual sub-areas (pixels) resulting from the rastering are assigned specific tone values.

The decomposition of the image template into subareas can be done using any raster form. Both simple, regular geometric structures and statistically distributed, irregular and complicated structures can be used. Just as well, the boundaries of the faces can be defined as desired.

Conceivable are, inter alia, parallel, nearly parallel, spiral, star-shaped, intersecting or entangled line systems with zigzag, wave, arc, circular or straight course, guilloches, geometric structures such as circles, ellipses, triangles and other polygons.

Of course, the various grid variants described the decomposition of a printed image in partial areas can also be combined with each other. The division of the image template into sub-areas is arbitrary and is subject only to the restriction that at least in a part of the printed halftone image printed sub-areas border each other.

The original image converted into partial areas with specific tone values are in turn assigned the engraving depths for the conversion of the original into an engraving on a gravure printing plate. The engraving depths are ink-dependent and are essentially determined by the transparency bandwidth of the ink to be used.

Various embodiments of the invention will be described by way of example with reference to the following examples.

example 1

If you want to get a lifelike image of the artwork, it is advisable to make a rasterized resolution of the original image. This variant is in Fig. 4 shown. The faces 6, 7, 8, 9 and 10 are thus obtained from the original image itself. This means that the faces are referenced to a pictorial section in the template. This is done automatically when creating halftone separations, where areas that correspond to a certain tonal range are assigned to faces, which are then rendered with a uniform tone. This leads to areally resolved image templates in which the respective tone values are subdivided into tone value ranges and each tone value range is represented by a defined tone value. For example, with five tonal ranges, the total range of tonal values 0-100% is divided into, for example, five equal parts, ie, 1-20%, 21-40%, 41-60%, etc. Then, each of the tonal ranges is superseded by, for example, the highest The tonal values of the individual areas are reproduced in a summarized manner, ie the tonal values ranging from 1 to 20% are represented by a uniform tone value of, for example, 20%, those from 21 to 40% by a tone value of 40% etc. The tone values of the example mentioned are thus 0%, 20%, 40%, 60%, 80% and 100%. The tonal ranges can also be chosen irregularly, eg 0%, 30%, 60%, 80%, 90%, 100%. In this case, for example, the brighter image areas are rated less strongly than the dark image areas. It should also be noted that a Tonwertauszug is usually not a contiguous 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 is a partial area according to the invention with the corresponding tone value to assign. The partial areas belonging to a tonal separation are distinguished by a uniform engraving depth or color layer thickness in the overall printed image. The grid superimposed on the image template is in this case exactly adapted to the boundary lines of the areas that represent certain tonal values. Looking at that in Fig. 4 As shown, for example, would result in three black faces 6, which have the dimensions of the black areas in the template. Furthermore, the corresponding partial areas would be for the dark (7), middle (8) and light gray (9) and white areas (10). The dimensions of the faces and thus the subsequent engraving thus arise directly from the image areas in the template. If the dimension of the sub-area and its associated tone value and the associated engraving depth are fixed, all the necessary data for a conversion of the original image into an engraving are known.

In the Fig. 4 shown black dividing lines 11 are normally not visible in the printed image. They serve only to better illustrate the boundaries of the sub-areas. In the printed image, in the area of these black lines, the faces are directly adjacent to each other without being separated by lines. When using a printing plate with the above-described separating edge, which extends to just below the printing plate surface, is in the range of in Fig. 4 shown black lines in the print image if necessary, a very fine bright, but occupied with color, ie printed line to see. In the case of the partial area 10 appearing white in the print image, provided there is a white substrate to be printed, this is an unprinted area in the otherwise full-surface printed image.

Example 2

In addition to the method described in Example 1, to determine the faces depending on the subject, but it is also possible to bring the template with a separately generated grid in coverage to produce the patches of the printed image. According to this embodiment, a raster will be laid over the original image, i. the image template is split into subareas completely independent of the subject. Tonal values are assigned to these partial areas which correspond to the partial areas in the later printed image according to the invention. The finer the grid, in other words, the smaller the partial areas that make up the continuous-tone image according to the invention, the more image details can be captured. These tone values are then converted into engraving depths for the printing plate as described above.

In the simplest case one uses a pixel grid. In Fig. 5 was the picture template off Fig. 2 superimposed with this grid. As a result, the image original is resolved into uniform quadratic surfaces 12. A partial area 12 is thus represented by a box / pixel. Fig. 5a shows as a detail Fig. 5 the section labeled "x". As explained in Example 1, the black lines in Fig. 5 and Fig. 5a only the delineation of the partial areas. They are not visible in the printed image as black lines. Each box or pixel is assigned a specific tone value in the next step. If several tonal values are present in a box, an average is formed, for example, via integration, which then determines the tonal value of the pixel. Since as a picture template the classic halftone picture according to Fig. 2 was used, arise with this method a variety of tonal values, which are converted into corresponding engraving depths.

In contrast to the known gravure printing plates, the engraving areas according to the invention are so closely adjacent for the pixels that the separation takes place only via separating edges described above. Although the separating edges in the pressure plate separate the individual pixels (wells) "physically" from one another, in terms of printing, however, they produce a direct transition from pixel to pixel despite the pasty printing ink. The pixels are thus not separated by unprinted webs, at best by lighter printed lines. These lines are usually extremely fine, so they do not stand out in the print image. The image created in this way is in Fig. 5b shown, in which case the individual boxes are already assigned the corresponding tonal values. The bright lines in Fig. 5b indicate how the separation edges are set in the engraving of the printing plate and how the partial surfaces in the printed image adjoin one another. They do not stand for completely unprinted lines.

To ensure the clarity of the presentation, the grid shown is kept relatively coarse. The image converted 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 grid with much smaller screen ruling, so that the generated pixels are much smaller and less perceived by the human eye as individual boxes.

Example 3

This in Fig. 6, Fig. 6a and Fig. 6b illustrated example is based as well as Example 2 on the use of a pixel grid. The difference, however, is that not the classic halftone picture is out Fig. 2 , but the halftone image constructed from halftone separations Fig. 3 overlaid with the grid.

As in Example 2, each pixel is assigned a particular tone. Since the original is limited to five tonal values, the image converted to pixels, as in Fig. 6a shown only five tonal values. That is, here the image is built up from a defined number of tonal values and corresponding engraving depths.

Fig. 6 shows the pixel halftone superimposed halftone image of five tone separations. Fig. 6a shows the in Fig. 6 indicated section "x", in which the assignment of the tonal values to the pixels already took place. Fig. 6b shows that too Fig. 6a associated print image, wherein one pixel corresponds to a partial surface 12.

The remarks in Example 2 apply analogously here.

Example 4

As in Fig. 7 are shown here starting from the semitone excerpts according to Fig. 4 again defined sub-areas, which are generated from the image motif itself. These are represented by the black lines 11. These partial surfaces then become the classic halftone image according to Fig. 2 superimposed. The individual sub-areas can then be assigned specific tone values which, in contrast to example 1, are not limited to just five tone values but can correspond to a multiplicity of tone values in the original. That is to say, the black partial surfaces 6, 6 'and 6 "are not implemented exclusively as black partial surfaces 6, as in Example 1, but can be further differentiated by different dark gray to black tonal values.The same applies to the dark gray partial surfaces 7 and 7' as well In addition, there is not only the possibility of assigning a specific tone value to a sub-area, but also the possibility of representing tone gradients within a sub-area optionally in addition with separating webs or dye-collecting webs, as for example 8 and Fig. 14 explained, are equipped.

Example 5

As in Fig. 8 shown, a line grid can be used as an alternative to the pixel grid, with which the halftone original superimposed thereon in accordance with Fig. 3 is divided into closely spaced strips 13. In this variant, the image template with horizontal parallel lines 11 is superimposed. In this case, however, a uniform tone value is not assigned to each stripe, but the tone value varies according to the tone extractions generated in step 2 within a stripe, as the tone separations vary along the stripe. A partial area is thus limited to the right and left and up and down by dividing lines 11 and in the printing plate by separating edges. The delimitation to the left and right results from the image motif and runs along the surfaces that have a certain tonal value, the dividing lines up and down arise from the superimposed line grid. Squares that do not fill a line across the entire width are either averaged over the line width and then mapped to the respective tone values according to the mean, or they are delineated within the strip with dividing lines, as shown.

Fig. 8a shows the in Fig. 8 with "x" designated portion in the exemplary three strips 13 are marked. Fig. 8b shows the printed image belonging to the section "x".

The bright borders of the partial areas in Fig. 8b serve again to illustrate the exact dimensions of the faces and suggest the use of separation edges in the pressure plate.

The strips and the areas within the strips, to which different tone values have been assigned, are here 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 strips, which are associated with a tone value, may have to be interrupted with further separating edges in order to avoid a "spraying" of the ink during the printing process. The separation edges may produce thin, light printed lines in the later printed image. If this is to be avoided, the so-called "color catching elements" within the raster lines also in the region of the printing plate surface, as in example 8 and Fig. 14 described, be provided. These do not protrude to the printing plate surface and occur in the later printed image less pronounced than the separating edges.

Example 6

In the Fig. 9 variant shown differs from that in Example 5 and Fig. 8 to 8b described embodiment in that as a template is not based on halftone separations image according to FIG. 3 but the classic halftone picture according to Fig. 2 overlaid with a line grid. The faces are, as in Example 5, separated by the individual lines 11 up and down from each other, with any number of tonal values, as in Fig. 9a clearly visible, can be present in the individual lines. Printing technology, the Tonwertverlauf is realized within a strip by means of a printing plate in which are engraved oblique planes within a strip, which in turn is delimited via separation edges to the next strip. Due to the inclined plane in the printing plate, a continuously increasing or decreasing ink layer thickness is produced on the data carrier, which a viewer 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, it is possible to engrave ink trapping structures to prevent bleeding or splashing between the Tonwertbereichen and lines. The bright lines in Fig. 9b show the demarcated by separating edges of partial areas in the printed image.

Example 7

Fig. 10 shows a variant in which the faces are defined by the free graphic design of the image template. Not the computationally determined tonal extracts from the photographic original, but the creative division of the template into partial areas determines the image according to the invention. Creative means, such as shades, colors, etc., become implemented by means of tonal values and partial areas. Fig. 10 shows in stylized form the in Fig. 2 Portrait portrayal shown, wherein four tonal values, namely white (10), light gray (9), dark gray (7) and black (6) are used.

Example 8

Unlike the in Fig. 10 shown eyebrow "y", which is in the simplest print image variant as a featureless black area show 10a and 10b various embodiments of the eyebrow "y", which are equipped with motif-dependent fine structures. In the associated printing plate, therefore, not only a corresponding eyebrow depression, but also an additional roughness pattern is engraved, which produces the desired fine structures in the print image.

Due to the shape and the guidance of the engraving tool, this roughness pattern can be generated at the bottom of the partial surfaces produced by the engraving, which firstly serves as a color trap for the printing ink and, on the other hand, influences the gloss and the visual impression of the printed or embossed image parts. The roughness basic pattern is, for example, according to the in WO 97/48555 described method in the engraving of the printing plate generated at the bottom of the cleared surfaces. For dimensions of the partial surfaces from a length and width of about 100 microns, for example, a color catch is appropriate. With engraving tools with large tip radius and round geometry and closely spaced Abräumahnen (for example, about 10 microns) to achieve smooth engraving, the smooth and trend tend to reflect reflective printing surfaces or embossing. On the other hand, if one chooses a small tip radius with a pointed cutting geometry for the engraving tool and further spaced-apart scraper webs (for example on the order of greater than 50 μm), rough, structured engravings are obtained which produce a matt and diffusely scattering printing surface or embossing.

On the one hand, the roughness pattern can be made uniform throughout the printed image, but it is also possible to change the clearing direction in individual subregions when engraving the depressions in the printing or embossing plate. Engravings engraved along linear scrapers, but rotated for example by 90 °, create visually distinguishable printing surfaces or imprints with different light reflections. The same applies to engraving with straight or meandering Abräumahnen compared to spiral or concentric Abräumahnen. These effects can not only be used for a more appealing or striking design of blind embossing or printing, but at the same time increase their counterfeit security. With the help of this deliberately used engraving technique, it is possible to superimpose fine structures on the printed or embossed area in a targeted manner, e.g. graphically support the image information, but these are clearly visible only at certain viewing angles or reflection angles or when viewed with a magnifying glass.

If one chooses the fine structures mentioned, as in 10a and 10b shown, alone by the nature of the engraving of the plate, for example, in addition to the eyebrow eyebrow hairs in the form of a fine structure can be effected. In Fig. 10a The engraving tool was guided concentrically along the contours of the clearing surface, while in Fig. 10b the engraving tool was guided on parallel lines. Other structures, such as oblique hatching, cross lattice, etc. are also possible.

Example 9

As explained in the introduction, the halftone image according to the invention already has a certain tactility due to the different color layer thicknesses and embossings of the paper substrate in the region of different tonal values. If the tactility in the printed image according to the invention is to be further enhanced, e.g. be produced according to Example 1 to 8 printed image with additional tactile structures. These structures are taken into account in the engraving of the intaglio printing plate, so that even in this variant, only one printing operation is necessary. The size of the structural elements, their tonality and their arrangement is to be considered for each individual case and aligned to the desired tactile and visual effects.

Fig. 11 schematically shows an inventive print image 20, which consists of a gray wedge and additional tactile structural elements. The gray scale has four squares 21, 22, 23, 24 with four different tonal values. Each square has an edge length of eg 5 mm and corresponds in each case to a partial surface.

Even this "halftone image" is tactile perceptible due to the relief structure of the printed image. Since the gray values are continuous from "dark" to "bright", the onset of the gray wedge, i. the black edge can be grasped tactfully. The further stages, however, are less perceptible, since they are sloping and changing only in small stages. In the basic motif smaller black circles 25, 26, 27, 28 are now incorporated into the squares as additional tactile structural elements. The additional structural elements are engraved much deeper than would be necessary for the representation of the tonal value "black". They therefore have a higher relief amplitude than the black partial surface 21 of the gray wedge. The structural elements 25 to 28 thus stand as a kind of "nubs" in the square partial surfaces. "Nubs" and partial surfaces are delimited in the printing plate by separating edges and appear accurately in the printed image. They can be felt from all directions in all sub-areas, even in the black, irrespective of the contrast or the gray value curve. The element 25 has optically 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. may be used as additional tactile features. The individual elements can be arranged arbitrarily in the basic motif. In the present case, a tactile structural element is centered in each partial area. But just as well in every second or third square a tactile structural element can be present. The structural elements may vary not only in shape but also in size. They can also have different tonal values.

In a further embodiment, for example, in Example 1 and Fig. 4 described partial surfaces are concretely delimited among themselves by means of tactile in the print image and possibly also visible enclosures. The in Example 1 and Fig. 4 described black and invisible Lines are tactile and visually perceptible in this variant. These are preferably lines with very dark tonal values, particularly preferably in black. This has the advantage that these lines are tactile perceptible relatively easily in the print image and can be used in the sense of the additional tactile structural elements. The lines themselves can vary in their thickness, for example, or they can be used only in a partial region of the image motif.

The tactility is advantageously enhanced by structural elements having a darker tonal value than the adjacent partial surface, since a darker tone value at the same time means a larger amplitude, which is composed of ink layer thickness and embossing, and thus can be easily tactually perceived. However, lighter tones are also possible. In this case, it has a positive effect on the tactility, if the structural elements with the lighter tonal values are not too small, since these are usually less embossed and thus harder to capture tactile than structural elements protruding from the printed image surface. The tactile structural elements are in the present example partly tactile and partly tactile and simultaneously visually perceptible. An only tactile perceptible structural element 25 is incorporated in the first square base 21. Here, both the structural element as well as the square base has the tonal value black, wherein the structural element was generated with a deeper engraving and thus has a higher amplitude than the base square. Structural element and base square have different ink layer thicknesses, wherein the ink layer thicknesses are chosen so large that the color is no longer translucent, and thus structure element and base square in plan view have the same tone and are visually indistinguishable. Depending on the design, the tactile elements may still be able to shine in the glancing angle due to different shadows be visible, even if they are not distinguishable from the ground in supervision. In this case, via the tactile structural elements a visible in the glancing angle information can be introduced, which can serve as an additional authenticity feature. If one thus wishes an additional tactile structure which should not be visible, structural elements must be selected which have the same tonal value as their surroundings, but which have a perceptibly distinguishable relief.

Since the tactile perception is a subjective sensation, a value from which a relief is perceived tactilely can only be determined within rough limits. The tactile perceptibility of a printed relief depends not only on the absolute relief height and the individual sensitivity, but also on the areal extent of the printed structure and on whether the printed structure to be felt is free-standing or integrated into a relief-like environment.

However, the following information can be given as rough guidelines. A pressure relief created in intaglio printing can be felt tactilely below a relief height of approx. 50 μm. Relief areas between approx. 50 μm and 60 μm are easy to feel. With relief amplitudes greater than 60 μm, the intaglio relief becomes clearly perceptible.

Fig. 11a shows an intaglio printing plate 30 according to the invention, with a printed image, as in Fig. 11 is shown along the section line AA produced. The engraving areas 31, 32, 33 and 34 each correspond to a square with incorporated tactile structural element. The respective squares as well as the structural elements are separated from one another by means of separating edges 39 which do not reach the printing plate surface. In the area 34 is additionally incorporated a color trap, which is shown as a zigzag pattern and the square 24 generates a surface texture (s. Fig. 11b ).

Fig. 11b shows in cross section a data carrier 40 with the in Fig. 11 shown print image along the section line AA. The substrate 50 has different degrees of embossing of the paper substrate and ink layers depending on the engraving depth in the printing plate. In the area of the black base square 21, a very strong embossing with a thicker paint application 41 takes place. Both the embossing and the ink application 42, 43, 44 decrease for the squares 22, 23, 24 which are lighter in tone and lie to the right. The additional tactile structural elements 25, 26, 27, 28 can be recognized as differently high bumps.

It should be noted that a relief on the data medium surface does not coincide identically with the engraving depth of the printing plate. This in Fig. 11b surface relief shown is reproduced idealized. The surface relief produced by the pressure is composed of a densification of the substrate material and the application of the ink layer. The overall height of the relief is based on the normal, ie unprinted and unembossed, data carrier surface. In practice, the relief produced on the substrate and the engraving present in the printing plate are very distinct from each other. The reason for the deviations between engraving depth and relief height is due to the fact that the disk is not pressed during the printing process to the bottom of the printing plate engraving and also the existing in the wells of the printing plate color is not completely transferred to the disk. Accordingly, the engraving depth of the printing plate for relief-like structures is in the range of about 40 μm to 250 μm, preferably in the range of about 55 μm to 150 μm. They produce relief structures in the range of about 5 microns to 100 microns, preferably 25 to 80 mμ. Whether an engraving depth lying on the surface of a data carrier leads to a rather relief-like or rather flat printing depends in individual cases on the steepness 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 print result depends not only on the engraving depth of the printing plate, but also on the properties of the substrate and the ink, in extreme cases, an engraving depth of 40 microns already lead to a relief-like print image, while in other material and printing parameters an engraving depth of 50 microns can still lead to a flat print image. In any specific application, however, the engravings leading to relief-like print image areas are always deeper than those which produce so-called flat, tactile non-tactile image areas.

Example 10

In the following FIGS. 12 to 14 Exemplary printing plates according to the invention and printed data carriers are described. The comments on this, in particular general descriptions of the inventive concept, are of course not limited to these specific variants.

In the Fig. 12 to 14 For example, sections of an engraved surface of an intaglio printing plate 60 according to the invention are shown schematically, with which a printed image according to Fig. 4 could be generated. Recess 61 in the printing plate has a very large engraving depth and generates in the printed image, for example, a black section. Right next to it separated, with a separating edge 39, an engraving area 62 with a lower engraving depth, which appears in the print image, for example light gray. Subsequent to the light gray partial surface, a middle gray partial surface follows, which corresponds to the engraving region 63 in the pressure plate. The subsequent dark gray area corresponds to a wide and in turn deep engraved area 64 in the printing plate. After an area 65 producing the tonal value of medium gray, the engraving area is closed with a surface 66 appearing light gray in the printed image. All engraving areas 61 to 66 are delimited by separation edges 39 against each other. In the Fig. 13 illustrated printing plate corresponds to the in Fig. 12 shown printing plate with the difference that the area 66 was additionally equipped due to its width with a color catch, which is indicated at the bottom of the engraving with a zig-zag pattern.

The associated to these printing plates printed media 70 is in Fig. 14 shown in cross section. The substrate 50, here banknote paper, is printed with glazed intaglio ink and deformed accordingly by the printing process. As explained above, deep engravings in the printing plate create heavily embossed areas with large ink coverage, while less deeply engraved areas imprint the medium less strongly, ie deform less, and in these areas, less ink is transferred from the printing plate to the medium. The in Fig. 12 61 denoted area corresponds to Fig. 14 the area 71. Clearly recognizable is the strong embossing and a thicker paint application. The indentation 79 on the right side thereof was created by the separating edge 39. The light gray printing area 72 with less ink application than in the area 71 adjoins the black area 71 seamlessly despite the separating edge in the printed image. The medium gray appearing areas 73 and 75 are again printed and embossed stronger. Significantly more marked and with a thicker Covered color layer, the area 74 appears dark gray in the print image. The region 76 is only slightly embossed and due to its low ink layer thickness it appears light gray in the printed image. The printed image surface shows in the area shown a pronounced relief structure, which is composed of the embossing and the paint application. This relief structure is also easily palpable for the layman and an unambiguous safety criterion.

Claims (19)

1. A security document or value document (1) having at least one halftone image produced by intaglio printing and representing a motif spatially, wherein the halftone image includes, in at least a partial region of the image, directly mutually adjacent partial areas (6-10) printed over the full area which respectively have a certain tonal value, wherein at least three of the printed partial areas mutually differ by their certain tonal value, and at least a partial region of the image is tactilely perceptible.
2. The security document or value document according to claim 1, characterized in that the halftone image renders a portrait (5).
3. The security document or value document according to claim 1 or 2, characterized in that the partial areas form a pixel grid.
4. The security document or value document according to claim 1 or 2, characterized in that the partial areas form a grid which is derived from the motif itself.
5. The security document or value document according to at least one of the above claims, characterized in that the partial areas are tactile.
6. The security document or value document according to at least one of the above claims, characterized in that the halftone image has additional tactile structure elements (25 to 28).
7. The security document or value document according to claim 6, characterized in that one tactile structure element is arranged in a partial area in each case.
8. The security document or value document according to claim 7, characterized in that the tactile structure element has a greater or smaller amplitude in comparison to the partial area.
9. The security document or value document according to at least one of claims 6 to 8, characterized in that the tactile structure element is not perceptible visually.
10. The security document or value document according to at least one of the above claims, characterized in that at least a portion of the partial areas is equipped with a roughness pattern which causes a visually distinguishable light reflection.
11. The security document or value document according to at least one of the above claims, characterized in that the halftone image has superimposed thereon, at least in partial regions, fine structures which influence its visual appearance and which have a different orientation in individual partial areas.
12. An intaglio printing plate (30) for producing a security document or value document by printing with a halftone image representing a motif spatially by means of at least one engraved region in the printing-plate surface, wherein the engraved region has, at least in a partial region, directly mutually adjacent partial areas (31 to 34) each with a certain engraving depth for a full-area print, wherein at least three of the partial areas mutually differ by their certain engraving depth.
13. The intaglio printing plate according to claim 12, characterized in that the directly mutually adjacent partial areas have identical or different engraving depths.
14. A security document or value document printed by means of the printing plate according to claim 12 or 13.
15. A method for producing a security document or value document having a halftone image representing a motif spatially, comprising the following steps:

    a) providing a data-carrier material for a security document or value document,

    b) producing an intaglio printing plate (30) according to claim 12 or 13, and

    c) printing the data-carrier material with the intaglio printing plate produced in step b).
16. The method for producing an intaglio printing plate (30) for the production of a security document or value document having a halftone image representing a motif spatially, comprising the following steps:

    a) converting a halftone image master representing a motif spatially into partial areas,

    b) assigning certain tonal values to the individual partial areas,

    c) assigning certain engraving depths to the tonal values for a full-area print,

    d) engraving the partial areas with the assigned engraving depth into the printing-plate surface such that, at least in a partial region, engraved partial areas are directly mutually adjacent and at least three of the engraved partial areas mutually differ by their certain engraving depth.
17. The method according to claim 16, characterized in that the partial areas are derived from a grid superimposed on the halftone image master (Figure 2).
18. The method according to claim 17, characterized in that the grid is a pixel grid.
19. The method according to claim 17, characterized in that the grid is derived from image information of the halftone image master.

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