Grid structure image for displaying a multicolored diffraction image

Description

[0001] The invention relates to a grating structure image for displaying a multi-coloured diffraction image, which has a plurality of grating image fields which glow in a desired colour when the grating structure image is illuminated, and which each contain one or more grating patterns made up of a multiplicity of grating lines to produce the desired colour, each of which is characterised by a grating constant and an azimuthal angular orientation.

[0002] Holograms, holographic grating images, and other hologram-like diffraction structures have been used for several years to authenticate credit cards, banknotes, and other valuable documents. Holographic diffraction structures are generally produced by embossing holographically generated grating images into thermoformable plastics or UV-curable lacquer on film substrates.

[0003] In true color holograms, the various color areas have so far usually been composed of three channels for the primary colors red, green, and blue, so that the desired true colors can be created by additive color mixing. However, the multi-channel mixed colors obtained in this way are often not very brilliant in practice. The primary colors themselves also appear to be rather poorly brilliant, since each color pixel contains partial areas for all three primary colors, and when only one primary color is displayed, the surface areas of the other two primary colors remain unoccupied. In addition, correct true color representation is generally only achieved within a narrow viewing angle, and tilting from an ideal viewing direction quickly results in incorrect colors that appear unnatural, particularly in portraits or depictions of nature. Even when true color holograms are rotated azimuthally, disturbing incorrect colors often occur even at small angles of rotation.

[0004] Micro-optical true-color images, on the other hand, are based on structural colors, such as photonic 2D crystals, plasmonic colors, ZOD colors, and the like. The color impression of such micro-optical true-color images is typically angle-independent, so no false colors arise when tilting or rotating. However, micro-optical true-color images are currently still very color-weak and pale, and are also difficult to produce.

[0005] DE 10 2013 105246 A1 discloses a security element for a security paper, value document or the like, a value document with such a security element and a method for producing such a security element.

[0006] Based on this, the invention is based on the object of specifying a lattice structure image of the type mentioned at the outset which can be produced on the large-scale required in the security sector and which, in addition to being highly secure against counterfeiting, has an attractive and bright appearance.

[0007] This object is achieved by the features of the independent claims. Further developments of the invention are the subject of the dependent claims.

[0008] According to the invention, in a generic lattice structure image, it is provided that the grating structure image contains a brilliance region whose area occupies more than 50% of the area of ​​the grating structure image occupied by grating image fields, wherein the grating image fields in the brilliance region consist of spectral color fields which each contain exclusively grating patterns of the same grating constant and shine in one spectral color when illuminated, at least four spectral color fields with different grating constants are provided in the brilliance region, which shine in different spectral colors when illuminated, and the spectral color fields of the brilliance region contain at least two sub-regions for the two eyes of a human observer, which each contain grating patterns of the same grating constant but with a slightly rotated azimuthal angular orientation in order to produce a color-constant image impression for the two eyes.

[0009] For further explanation, the grating structure image contains, on the one hand, a grating region formed by the area of ​​the grating structure image occupied by grating image fields, and, on the other hand, a normal region formed by the area of ​​the grating structure image not occupied by grating image fields. The normal region typically contains a dark background, reflective partial areas, or image fields that do not contain grating structures, such as micromirror image fields.

[0010] According to the invention, the grating region of the grating structure image now contains a so-called brilliance region in which the grating image fields consist of spectral color fields, i.e. single-channel grating image fields, each of which contains exclusively grating patterns of the same grating constant and which glow in one spectral color when illuminated. In addition, at least four spectral color fields with different grating constants are provided in the brilliance region, and the spectral color fields of the brilliance region each have at least two sub-regions with the properties described above for the two eyes of a human observer. The brilliance region can, but does not have to, be contiguous. Essentially, the brilliance region represents a designation for the surface area of ​​the grating structure image in which the grating image fields have the properties described above.

[0011] The brilliance region is essentially responsible for the brilliant and luminous appearance of the grating structure image and, according to the invention, occupies more than 50% (or more than 75%, or 85%, or 95% in preferred embodiments) of the area of ​​the grating region. The remaining area of ​​the grating region, less than 50% (or less than 25%, 15%, or 5% in preferred embodiments), is occupied by other grating structures, for example, with multi-channel, in particular two- or three-channel grating image fields, or with single-channel grating image fields that do not meet the requirements for the spectral color fields of the brilliance region, as explained in more detail below.

[0012] Advantageously, the spectral color fields of the brilliance range are formed by freeform surfaces of irregular and varying shapes and sizes. In particular, the spectral color fields do not represent pixelation or tiling of the surface of the grid structure image, as these require the surface to be covered with one or a few similar, simple geometric surface elements.

[0013] The grating patterns of the aforementioned sub-regions are advantageously rotated relative to one another by 4° to 20°, preferably by 6° to 12°, particularly preferably by approximately 8°. The rotation is generally achieved by rotating the azimuthal angular orientation of the grating pattern of one of the two sub-regions by a specific offset clockwise (for one eye), and the azimuthal angular orientation of the grating pattern of the other sub-region by the same offset counterclockwise (for the other eye) relative to the angular orientation θ provided for the spectral color field. This offset is preferably between 2° and 10°, or between 3° and 6°, preferably approximately 4°; the rotation of the two grating patterns relative to one another then corresponds to twice the offset value.

[0014] The division of the spectral color fields into subregions is preferably achieved by dividing them into narrow strips or small pixel elements. In an advantageous embodiment, the subregions are formed by alternating strips. The width of the strips is expediently below the resolution limit of the human eye, in particular below 100 µm or even 50 µm or less. In another, equally advantageous embodiment, the subregions are formed by nested pixel elements. The lateral dimensions of the pixel elements are expediently below the resolution limit of the human eye, in particular below 100 µm or even 50 µm or less.

[0015] Advantageously, spectral color fields with different grating constants are provided in the brilliance range between 4 and 32, preferably between 8 and 20, particularly preferably between 12 and 20.

[0016] In a further embodiment, the grating structure image can contain a spectral color gradient in a sub-area of ​​the brilliance range, formed by several adjacent spectral color fields with only slightly varied grating constants. In particular, the grating constant changes from one spectral color field to the next by less than Δd = 10 nm.

[0017] In a particularly advantageous embodiment, the spectral color patches of the brilliance range have lateral dimensions of more than 150 µm in at least one lateral direction and are visible to the naked eye. In this case, spectral color patches may also be present outside the brilliance range that have dimensions of 150 µm or less in all lateral directions.

[0018] The said spectral color fields of the brilliance range preferably even have dimensions of more than 250 µm, in particular of more than 500 µm, in at least one lateral direction, preferably in every lateral direction.

[0019] The brilliance region preferably occupies an area of ​​more than 75%, in particular more than 85% of the area of ​​the grating structure image occupied by grating image fields.

[0020] The grating lines of the grating patterns advantageously have a sinusoidal profile, a symmetrical triangular profile (sawtooth profile), an asymmetrical triangular profile (blazed profile), or a rectangular profile (binary structure). It goes without saying that any other profiles can also be used, although sawtooth profiles have proven particularly effective due to their particularly high luminosity, and sinusoidal profiles have proven themselves due to their reliable manufacturing.

[0021] In the brilliance range, at least some of the spectral color fields, or sub-regions of at least some of the spectral color fields, can also be only partially covered with grating patterns to create spectral color fields of different brightnesses. The grating structure image advantageously contains at least one light / dark gradient generated by such only partially covered spectral color fields to give the color areas of the diffraction image a three-dimensional appearance.

[0022] In an advantageous embodiment, the grating structure image has two- or three-channel grating image fields in the area occupied by grating image fields outside the brilliance range, which, when illuminated, glow in non-spectral colors, in particular in an achromatic color such as white or a shade of gray. At least some of the two- or three-channel grating image fields can also be only partially covered with grating patterns in order to generate non-spectral colors of different brightnesses.

[0023] In an advantageous embodiment, the grating structure image comprises, in addition to the grating image fields, also micromirror image fields that are not provided with grating structures, but rather with an arrangement of directionally reflecting micromirrors. The micromirrors of a micromirror image field are preferably all tilted in the same direction at a desired angle relative to the surface of the grating structure image and generate a particularly bright image field in the corresponding viewing direction. The edge length of the micromirrors is at least 5 µm. To avoid or at least minimize diffractive color splitting effects, the micromirrors are advantageously arranged quasi-periodically or aperiodically and / or with aperiodically or even irregularly varying shape and / or size.

[0024] The invention also includes a security element or a data carrier with a grid structure image of the type described above. The security element can in particular be a security thread, for example a window security thread, a pendulum security thread, or a tear-off thread, but can also be a wide security band, a security strip, a patch, or a label for application to a security paper, valuable document, or the like. The security element can be arranged over a window or a see-through area of ​​a data carrier and can then preferably be designed for a two-sided display.

[0025] The data carrier may in particular be a value document, such as a banknote, in particular a paper banknote, a polymer banknote or a foil composite banknote, a share, a bond, a certificate, a voucher, a cheque, a high-value admission ticket, but also an identification card, such as a credit card, a bank card, a cash payment card, an authorization card, an identity card or a passport personalisation page.

[0026] The grating structure image can, in particular, be combined with one or more elements from the group consisting of matte structures, moth-eye structures, micromirror structures, stereograms, and volume holograms. Hidden information can also be provided in a sub-area of ​​the grating structure image. For example, a sub-area of ​​a grating image field can contain an area not covered by grating patterns, which contains additional information that can only be perceived with aids such as a microscope.

[0027] Further embodiments and advantages of the invention are explained below with reference to the figures, in which a true-to-scale and true-to-proportion reproduction has been omitted in order to increase clarity.

[0028] They show: Fig. 1 a schematic representation of a banknote with a security element containing a grating structure image according to the invention for displaying a multi-coloured diffraction image, Fig. 2 a section of the multi-coloured image motif of the Fig. 1 in the head area of ​​the motif "Ara", Fig. 3 an enlarged detail of the Fig. 2 in a schematic representation, Fig. 4 a more detailed representation of a single spectral color field of the brilliance range of a grating structure image according to the invention, Fig. 5 a representation as Fig. 4for another embodiment of the invention, Fig. 6 in (a) to (d) illustrations for the partial coverage of rectangular sub-areas of spectral color fields with grid patterns, Fig. 7 in (a) to (d) illustrations for the generation of white-luminous grid image fields, Fig. 8 in (a) to (g) illustrations for the generation of gray-luminous grid image fields, and Fig. 9 a combination of several of the elements described above in a grid structure image, Fig. 10 in (a) and (b) a representation as in Figures 4 and 5 for further embodiments of the invention.

[0029] The invention will now be explained using the example of security elements for banknotes. Figure 1shows a schematic representation of a banknote 10 with a security element 12 containing a grating structure image 14 according to the invention for displaying a multicolored diffraction image. The grating structure image 14 of the exemplary embodiment produces a brilliant and luminous image of a macaw when illuminated with white light. Compared to conventional true-color holograms, it is particularly striking that the color brilliance of the diffraction image is stable over a comparatively large angular range, and hardly any off-colors occur.

[0030] The structure of the lattice structure image 14 and the creation of the brilliant, multi-colored appearance are now described with reference to the Figures 2 and 3 explained in more detail. Figure 2 shows a section 16 of the multi-coloured image motif in the head area of ​​the macaw in black and white and Fig. 3 shows an enlarged detail 18 of the Fig. 2 in schematic representation.

[0031] The grating structure image 14 has a plurality of grating image fields 20, which glow in a desired color when the grating structure image is illuminated with white light. To generate the desired color, the grating image fields 20 each contain a grating structure, namely one or more grating patterns, each of which is characterized by a grating constant d and an azimuthal angular orientation θ ( Fig. 3 ) are characterized.

[0032] In the exemplary embodiment, the colors of the grating image fields 20 are based on illumination with the standard light source D65 and perpendicular viewing. Under these conditions (and when viewed in a viewing direction adapted to the azimuthal angular orientation of the grating patterns), for example, grating image field 22-1 glows yellow, grating image field 22-2 orange, grating image field 22-3 blue, grating image field 22-4 green, grating image field 24-1 light gray, and grating image field 24-2 white. The exact, actually perceived color impression depends on the type of light source and the viewing angle, so that the color impression under other viewing conditions may differ slightly from the color impression of the design conditions.

[0033] A particularly luminous image impression is created in this case because a large portion of the surface area of ​​the grating structure image 14 covered by grating image fields 20 is not occupied by multi-channel grating image fields 24-1, 24-2, but rather by single-channel spectral color fields 22, each of which contains exclusively grating patterns of the same grating constant. Therefore, when illuminated, these single-channel spectral color fields do not glow in a mixed color, but rather in a spectral color determined by the grating constant.

[0034] In the exemplary embodiment, eight different types of spectral color fields 22 are provided, which each differ in the grating constant of the grating patterns they contain and which therefore shine in different spectral colors when illuminated.

[0035] The spectral color fields 22 each have dimensions of more than 150 µm in at least one lateral direction and are recognizable to the naked eye as monochrome spectral color fields. A further special feature is that the shape and size of the spectral color fields 22 are not regular, i.e., the spectral color fields do not represent pixelation or tiling of the surface with similar, simple geometric surface elements. On the contrary, the spectral color fields 22 each represent free-form surfaces with irregular and varying shapes and sizes, as in Figures 2 and 3 visible.

[0036] The above-mentioned properties of the spectral color fields 22 are shown in the schematic detail section 18 of the Fig. 3illustrated again. The spectral color fields 22 each contain grating patterns 26 made up of a plurality of grating lines, which are characterized by a grating constant d and an azimuthal angular orientation θ relative to a reference direction R. Within each spectral color field 22, there are exclusively grating patterns with the same grating constant. Different spectral color fields 22-1, 22-2 can, however, contain grating patterns with different grating constants, wherein, as mentioned, eight different grating constants are represented in the exemplary embodiment, which produce different spectral colors between red (largest grating constant) and blue (smallest grating constant). The spectral color fields 22 each have macroscopic dimensions, thus being recognizable as such with the naked eye from a viewing distance of 20 to 50 cm, which is typical for holographic security elements.

[0037] The azimuthal angular orientation θ of the grid patterns determines the viewing direction from which the corresponding grid image fields 20 are visible. The azimuthal angular orientations θ of the grid image fields belonging to the "Ara" image motif are therefore coordinated such that these grid image fields illuminate simultaneously from a desired viewing direction and together form the "Ara" image motif.

[0038] In addition to the previously discussed single-channel spectral color fields 22, which in the exemplary embodiment form a brilliance range that occupies more than 80% of the area of ​​the grid structure image occupied by grid image fields, the "Ara" image motif also contains several multi-channel grid image fields, such as the light gray grid image field 24-1 or the white grid image field 24-2. Such multi-channel grid image fields serve to display non-spectral colors, in particular the achromatic colors white and the various shades of gray.

[0039] The brilliance range with the spectral color fields 22 and the area occupied by the multi-channel grating image fields 24-1, 24-2 together form the grating range of the grating structure image. In addition, the grating structure image 14 also contains a normal range without grating structures, which in the exemplary embodiment is formed by the black background of the Ara display.

[0040] These non-spectral colors are generated in the exemplary embodiment by two-channel or three-channel grating image fields. Particularly bright, highly reflective areas can also be generated by image fields with micromirror structures, as explained in more detail elsewhere. In the present invention, however, the image fields representing non-spectral colors are of secondary importance, since the brilliant color impression of the diffraction image is created by the high surface area of ​​bright, colored spectral color fields. The multi-channel grating image fields and the micromirror image fields merely serve to complete the color representation of the image motifs in smaller sub-areas, if necessary.

[0041] Another important feature of the grating structure image 14 is that the spectral color fields 22 in the brilliance range of the grating structure image 14 are designed and adjusted for binocular viewing by a human observer.

[0042] For further explanation, see Fig. 4 A single spectral color field 30 of the brilliance range of a grating structure image is selected and illustrated in more detail. As shown there by way of example, the spectral color fields 30 in the brilliance range of the grating structure image according to the invention each contain at least two strip-shaped, alternately arranged sub-regions 32, 34 for the two eyes of a human observer, each containing grating patterns 36 and 38, respectively, of the same grating constant but with a slightly rotated azimuthal angular orientation θ 1 , θ 2 .

[0043] When viewing the grid structure image 14, the right and left eyes of a viewer see each spectral color field 30 at slightly different angles due to the interpupillary distance of typically (on average) approximately 65 mm. This often results in a slightly different color impression for the two eyes with conventional grid images. Even small tilts or rotations from the ideal viewing angle can produce incorrect colors, which is usually undesirable and can appear slightly unnatural, especially in portraits or nature depictions.

[0044] This problem is taken into account in the present invention by the mutually rotated azimuthal angular orientation of the grating patterns 36, 38 in the strip-shaped sub-regions 32, 34, and an image impression of high color constancy is created, ie the same image is displayed with constant color for both eyes. In the exemplary embodiment, the grating patterns 36, 38 of the alternating stripes 32, 34 are each rotated by +4° or -4° relative to the angular orientation θ provided for the spectral color field 30. The grating pattern 36 of the stripes 32 therefore has a grating constant d and an angular orientation θ 1 = θ + 4°, while the grating pattern 38 of the stripes 34 has the same grating constant d, but an angular orientation θ 2 = θ - 4°. The two grating patterns 36, 38 are therefore offset by Δθ = |θ 1 - θ 2 | = 8° relative to each other. This aligns the color impression of the spectral color field 30 for the viewer's two eyes.D The visibility of the grid structure image 14 is increased in this way and, in particular, increased color stability is achieved when tilting or azimuthally rotating the grid structure image 14.

[0045] Unlike the spectral color field 30 itself, the striped sub-regions 32, 34 are not intended to be visible to the naked eye. They therefore have a width B below the resolution limit of the naked eye, for example, a width B = 25 µm.

[0046] The sub-areas can also have a different shape than the one in Fig. 4 The further embodiment of the Fig. 5 shows a checkerboard-like division of the spectral color field 40 into small, rectangular sub-areas 42, 44 with a dimension of 25 x 25 µm 2< except for the edge areas. The sub-areas 42, 44 contain, as in Fig. 4grating patterns 36 and 38 respectively with the same grating constant, but with a slightly rotated azimuthal angular orientation.

[0047] In addition, other tiling of the plane can be considered for the division into sub-areas, i.e. a gapless and overlap-free covering of the area of ​​a spectral color field by uniform tiles. The further embodiment of the Fig. 10(a) a division of the spectral color field 100 into small, cross-shaped sub-areas or tiles 102, 104, each composed of five 10 x 10 µm 2< squares. The sub-areas 102, 104 contain, as in Fig. 5 grating patterns 36 and 38 respectively with the same grating constant, but with a slightly rotated azimuthal angular orientation.

[0048] In the embodiment of the Fig. 10(b)The sub-areas or tiles 112, 114 of the spectral color field 110 are each formed in the shape of a motif (here, a cat). For simplicity, the different azimuthal angular orientations of the grid patterns contained in the sub-areas 112, 114 are illustrated only by the different colors of the sub-areas 112, 114.

[0049] The tiles of a parquetry can all have the same shape, as in the Figures 4, 5 and 10 As shown, it is also possible to create a tiling from several different tiles. One example is the so-called Penrose tiling, in which two different diamonds are used to cover the spectral color fields seamlessly and without overlap.

[0050] While the small sub-areas of the spectral color fields that are not visible to the naked eye can represent a regular tiling, the large spectral color fields that are visible to the naked eye do not represent a tiling themselves, but rather have irregular shapes of different shapes and sizes.

[0051] By using several adjacent spectral color fields with only slightly varied grating constants, spectral color gradients can also be created in the grating structure image.

[0052] Spectral color patches completely covered with grid patterns exhibit the highest achievable brightness and brilliance. By only partially covering the spectral color patches, or by only partially covering sub-areas of the spectral color patches, different brightnesses or brilliances can be created, and by combining different coverages, even brightness gradients can be created.

[0053] Figure 6illustrates only partial coverage of rectangular sub-areas 50 of spectral color fields with grid patterns 52. Figure 6(a) shows a full-surface coverage with the grid pattern 52 and Figures 6(b), 6(c) and 6(d) Each shows a partial grid pattern coverage of different geometries. The smaller the area coverage with grid lines in a sub-area 50 and the larger the unoccupied area portion 54, the darker and less brilliant the color representation. With the help of such partially occupied sub-areas 50, light / dark gradient representations can be created, which lend the color areas of the grid structure image 14 a particularly three-dimensional appearance.

[0054] It is understood that such partial coverage can also be used for irregularly shaped sub-areas and for sub-areas in the form of free-form surfaces, such as those shown in Fig. 10(a)shown cross-shaped sub-areas 102, 104, or the Fig. 10(b) shown cat-shaped sub-areas 112, 114.

[0055] Figure 7 illustrates the generation of the already mentioned white glowing grid image fields, which are intended to be used in a small area. With reference to Fig. 7(a) and 7(b) White surfaces can be generated by three-channel color surfaces 60, which contain three grid patterns 62-B, 62-G, and 62-R for the primary colors blue, green, and red, and which together produce white through additive color mixing. Alternatively, a white surface can also be generated by two-channel color surfaces 64, which contain two grid patterns with complementary spectral colors, for example, cyan (grid pattern 66-C) and red (grid pattern 66-R) in Fig. 7(c) , or yellow (grid pattern 66-G) and blue (grid pattern 66-B) in Fig. 7(d) contain.

[0056] To generate grey luminous grid image fields, with reference to Fig. 8Three-channel color areas 80 are used, in which the three grid patterns 82-B, 82-G and 82-R for the primary colors blue, green and red are each present in only one partial area. Figures 8(a) to (e) show several examples of different geometric arrangements of the partial areas 82-B, 82-G and 82-R covered with grid patterns. Alternatively, a grey luminous area can also be generated by a two-channel colour area 84, which in each partial area contains two grid patterns for complementary spectral colours, for example cyan (grid pattern 86-C) and red (grid pattern 86-R) in Fig. 8(f) , or yellow (grid pattern 86-G) and blue (grid pattern 86-B) in Fig. 8(g) and 8(h) contain.

[0057] Figure 9 illustrates the combination of several of the above-mentioned elements in a lattice structure image. Specifically, the figure shows a combination of a single-channel spectral color field 30 with strip-shaped sub-areas 32, 34 according to Fig. 4with a three-channel white pixel 60 to Fig. 7(a) , a two-channel white pixel 64 after Fig. 7(d)and a sub-area 90 occupied by a micromirror array. The area of ​​spectral color field 30 excluding sub-area 90 belongs to the grating area of ​​the grating structure image, while the sub-area 90 not occupied by grating structures belongs to the normal area. Within the grating area, the area of ​​spectral color field 30 excluding the areas of three-channel pixel 60, two-channel pixel 64, and sub-area 90 belongs to the brilliance area. The areas of multi-channel pixels 60 and 64 belong to the grating area, but not to the brilliance area, since the latter only contains single-channel spectral color fields. By combining spectral color fields, grating image fields with mixed colors, particularly white or gray grating image fields, and micromirror image fields with micromirror arrays, a variety of visually attractive holographic image motifs can be created. List of reference symbols

[0058] 10 Banknote 12 Security element 14 Grid structure image 16 Detail 18 Detail 20 Image fields 22 Spectral color fields 22-1, 22-2, 22-3, 22-4 Spectral color fields 24-1, 24-2 Multi-channel image fields 26 Grid pattern 30 Spectral color field 32, 34 Sub-areas 36, 38 Grid pattern 40 Spectral color field 42, 44 Sub-areas 50 Sub-area 52 Grid pattern 54 Unoccupied area portion 60 Three-channel color areas 62-B, 62-G, 62-R Grid pattern 64 Two-channel color areas 66-C, 66-R Grid pattern 80 Three-channel color areas 82-B, 82-G, 82-R Grid pattern 84 Two-channel color areas 86-C, 86-RGlating pattern 90partial area covered with micromirror array 100spectral color field 102, 104sub-areas 110spectral color field 112, 114sub-areas dlattice constant θ, θ 1 , θ 2 azimuthal angular orientation Δθrotation against each other BWidth

Claims

1. Grating structure image (14) for representing a multicoloured diffraction image, having a plurality of grating image fields (20) which shine in a desired colour when the grating structure image (14) is illuminated and which, in order to generate the desired colour, each contain one or more grating patterns composed of a plurality of line grating lines, each characterized by a grating constant (d) and an azimuthal angle orientation (θ), wherein the azimuthal angle orientation (θ) defines the viewing direction from which the grating image fields (20) are visible, characterized in that - the grating structure image (14) contains a brilliance region, the area of which takes up more than 50% of the area of the grating structure image (14) occupied by grating image fields, wherein - the grating image fields (20) in the brilliance region consist of spectral colour fields (22) which each exclusively contain grating patterns of the same grating constant and shine in a spectral colour upon illumination, - at least 8 spectral colour fields having different grating constants are provided in the brilliance region, and shine in different spectral colours upon illumination, and - the spectral colour fields of the brilliance region are formed by freeform areas having irregular and different shapes and sizes.

2. Grating structure image according to Claim 1, characterized in that the azimuthal angle orientations of the grating patterns are coordinated with one another such that the grating image fields light up simultaneously from a desired viewing direction.

3. Grating structure image according to Claim 1 or 2, characterized in that between not less than 8 and not more than 32, preferably between not less than 8 and not more than 20, particularly preferably between not less than 12 and not more than 20, spectral colour fields having different grating constants are provided in the brilliance region.

4. Grating structure image according to at least one of Claims 1 to 3, characterized in that the grating structure image contains in a partial region of the brilliance region a spectral colour profile formed by a plurality of mutually adjacent spectral colour fields having a grating constant that is varied only to a small extent.

5. Grating structure image according to Claim 4, characterized in that the grating constant changes from one spectral colour field to the next by less than 10 nm.

6. Grating structure image according to at least one of Claims 1 to 5, characterized in that the spectral colour fields of the brilliance region have lateral dimensions of more than 150 µm in at least one lateral direction and are discernible with the naked eye.

7. Grating structure image according to Claim 6, characterized in that the spectral colour fields of the brilliance region have dimensions of more than 250 µm, preferably more than 500 µm, in at least one lateral direction, preferably in each lateral direction.

8. Grating structure image according to at least one of Claims 1 to 7, characterized in that the brilliance region takes up an area of more than 75%, in particular more than 85%, of the area of the grating structure image occupied by grating image fields.

9. Grating structure image according to at least one of Claims 1 to 8, characterized in that in the brilliance region at least one portion of the spectral colour fields are only partly occupied by grating patterns in order to generate spectral colour fields of different brightnesses.

10. Grating structure image according to Claim 9, characterized in that the grating structure image in this case contains at least one bright / dark progression generated by means of only partly occupied spectral colour fields, in order to impart a plastic impression to the colour areas of the diffraction image.

11. Grating structure image according to at least one of Claims 1 to 10, characterized in that the grating structure image, in the area occupied by grating image fields outside the brilliance region, has two- or three-channel grating image fields which shine in non-spectral colours, in particular in an achromatic colour, upon illumination.

12. Grating structure image according to Claim 11, characterized in that at least one portion of the two- or three-channel grating image fields is only partly occupied by grating patterns in order to generate non-spectral colours of different brightnesses.

13. Grating structure image according to at least one of Claims 1 to 12, characterized in that besides the grating image fields the grating structure image also has micromirror image fields provided with an arrangement of directionally reflective micromirrors.

14. Security element or data carrier comprising a grating structure image according to any of Claims 1 to 13.

15. Security element or data carrier according to Claim 14, characterized in that the grating structure image is combined with one or more elements of the group consisting of matt structures, moth-eye structures, micromirror structures, stereograms and volume holograms.