KR20050020771A - Security Element with Micro- and Macrostructures - Google Patents

Abstract

A difficult-to-copy security member having a layered composite having a microscopically microscopic optical effect structure (9) of the surface pattern, wherein the optically effective structure is comprised between two layers (5; 6) of the layered composite (1). Engraved on. In the plane of the surface pattern defined by the axes x, y, the optical effect structure 9 is connected to the interface 8 between the two layers 5; 6 in the surface portion of the security feature which is not holographically copyable. It is shaped. In at least one surface portion, the optical effect structure 9 is a diffractive structure S, S ^* , S ^* formed by superposition that combines a microscopic superposition function M with a microscopically fine relief profile R. ^* ). Both the relief profile R and the superposition function M, and the diffractive structures S, S ^* , S ^** are functions of the coordinate axes x, y. The relief profile R is a light diffraction or light scattering optical effect structure 9 and has a predetermined profile height along the superposition function 9. The superposition function M is at least partially steady, not a periodic triangular or square function. Compared with the relief profile R, the superposition function M changes slowly. When the layer composite 1 is rotated or tilted, the observer sees the light of the irradiated surface part continuously moving along the visual direction.

Description

Security element with micro- and macrostructures

The present invention relates to a security element as disclosed in the preamble of the claims.

Such a security member includes a thin layer composite made of plastic material, the thin layer composite having at least diffraction structures, light-scattering structures, and flat mirror surfaces. Relief structures selected from the group consisting of are embedded. A security member cut out of the thin layer composite is attached to the article to ensure the reliability of the article.

The structure of the thin layer composite and the materials used for it are disclosed in US Pat. No. 4,856,857. It is also known from British Patent Publication No. 2 129 739A that the thin layer composite is applied to an article by a carrier film.

Those of the kind referred to at the outset of this specification are known from EP 0 429 792 B1. The security member attached to the document has a surface pattern that can be optically changed. An example of such a pattern is known from European Patent Publication No. 0 105 099, which is arranged in a mosaic form such as a known diffractive structure. It includes a surface portion. In order to mimic apparent credibility, a security profile is used to adjoin the security element with the true document, so that a fake security element that is removed from the true document or cut out from the true document is not provided in the fake document without a clear trace. It is made in the form of embossing on the portion. A true document is distinguished by the security profile extending seamlessly from the security member to the vicinity of the document. Embossing security profiles conflicts with recognizing optically changing surface patterns. In particular, the position of the embossed punch on the security member depends on the document.

Security members are known which make it difficult or nearly impossible to imitate or copy using conventional holographic means. For example, EP 0 360 969 A1 and WO 99/38038 disclose an arrangement of an asymmetric optical grating.

The surface member has a grating used at different azimuth angles, which form a pattern that is controlled in terms of brightness within the surface pattern of the security member. The pattern adjusted in relation to the brightness is not reproduced within the holographic copy. If, as disclosed in WO 98/26373, the structure of the grating is smaller than the wavelength of light used for copying, such a submicroscopic structure (submicroscophic structure) is no longer detected and therefore, It does not play in copies in the same way.

The protective arrangement for preventing holographic radiation, disclosed in European Patent Publication Nos. 0 360 969 A1, WO 98/26373 and WO 99/38038, which are mentioned by way of example, is a significant difficulty in terms of production engineering. You have to go through to achieve this.

Preferred configurations of the invention are disclosed in the claims. Next, an embodiment of the present invention will be described in more detail with reference to the accompanying drawings.

1 is a cross-sectional view of the security member.

2 is a plan view of the security member.

3 shows reflection and diffraction at the grating.

4 is a view showing the illumination and observation in the security member.

5 is a view showing reflection and diffraction in the diffraction structure.

6 shows security features at various inclination angles.

7 shows a diffraction structure and a superimposition function in a cross section.

8 is a view showing orientation of the security member by the identification mark.

9 is a diagram showing the local angle of the slope in the superposition function.

FIG. 10 is a diagram showing that the security member is settled according to the color tone contrast in the security characteristic.

11 shows a diffractive structure with a symmetric overlap function.

12 shows a security feature with color change.

13 shows an asymmetric overlap function.

It is an object of the present invention to provide a low cost new security member which can prevent to a high degree a counterfeit attempt, for example a holographic copying process.

The above object is composed of a layer composite having a microscopic microscopic optical effect structure of a surface pattern, the optical effect structure being engraved between the layers of the layer composite, wherein the optical effect structure is defined by coordinate axes. In a security member formed of a reflective interface between the layers within a surface portion of a security feature in the plane of a defined surface pattern, at least one surface portion of size greater than 0.4 mm has a superposition function that defines a macroscopic structure. Having a diffractive structure formed by addition or subtraction superimposition on the scopic micro relief profile, the superposition function, the relief profile and the diffraction structure define a light-diffraction or light-scattering optical effect structure, the optical effect structure defining the superposition function Thus, you will have a preset relief profile, Partly in a superimposed steady hamsueun at least some sections has a gradient, but to a periodic triangular or rectangular function is not, in comparison with the relief profile is achieved by a security element, characterized in that the changing slowly.

Referring to Fig. 1, member number 1 represents a layer composite, member number 2 represents a security member, member number 3 represents a substrate, member number 4 represents a cover layer, and member number 5 represents a molding layer. (shaping layer), the member number 6 represents a protective layer, the member number 7 represents an adhesive layer, the member number 8 represents a reflecting interface, and the member number 9 represents an optically effective structure. Reference numeral 10 designates a transparent position in the reflective interface 8. The layer composite 1 comprises a plurality of layer parts consisting of various plastic layers which are sequentially applied to a carrier film (not shown), in which a cover layer 4, a molding layer 5, a protective layer ( 6) and the adhesive layer 7 in this order. The cover layer 4 and the shaping layer 5 are transparent to the incident light 11. If the protective layer 6 and the adhesive layer 7 are also transparent, a mark (not shown) applied to the surface of the substrate 3 can be recognized through the transparent position 10. In one embodiment the cover layer 4 itself functions as a carrier film, but in another embodiment a carrier film is applied to the substrate 3 which functions to be applied to the thin layer composite 1, after which the layer composite 1 is applied. Is removed from. This example is disclosed in British Patent Publication No. 2 129 739A.

The common contact surface between the shaping layer 5 and the protective layer 6 is the interface 8. The optical effect structure 9 is formed in the shaping layer 5 in an optically changeable pattern having a structure height H _St. Since the protective layer 6 fills the valley of the optical effect structure 9, the interface 8 has the same shape as the optical effect structure 9. In the optical effect structure 9, in order to achieve a high level of effect, the interface 8 is a metal coating, preferably US patent, as a reflective layer separating the shaping layer 5 and the protective layer 6. 4,856,857 having a metal coating composed of the elements disclosed in Table 5, in particular aluminum, silver, gold, copper, chromium, tantalum and the like. The electrical conductivity of the metal coating provides a high level of reflection capability with respect to visible incident light 11 at the interface 8. However, instead of the metal coating, a plurality of layers made of any of the known transparent inorganic dielectrics listed in, for example, Tables 1 and 4 of US Pat. No. 4,856,857 are also suitable. The reflective layer also has a multilayer interference layer, for example a double layer metal-dielectric combination or a metal-dielectric-metal combination. In an embodiment, the reflective layer is structured so as to partially cover the interface 8 only in a predetermined area of the interface 8.

The layer composite 1 is produced from a plastic laminate in the form of a long film web having a number of copies in which optically changing patterns are mutually juxtaposed. The security member is for example cut out of the film web and attached to the substrate 3 by the adhesive layer 7. The substrate 3 is mostly in the form of a document, check, bank card, identification card or other important or valuable article, which is provided with a security member 2 to ensure the reliability of the article. do.

2 shows the part of the substrate 3 with the security member 2. The surface pattern 12 can be seen through the cover layer 4 (FIG. 1) and the shaping layer 5 (FIG. 1). The surface pattern 12 is arranged in a plane defined by coordinate axes x, y and has a security feature 16 comprising at least one surface portion 13, 14, 15. The outer surface 13, 14, and 15 may be clearly seen through the naked eye. That is, the shape and size of the surface portion are larger than 0.4 mm in at least one direction. In FIG. 2 the security features 16 are indicated by double outlines due to the relevance of the other figures. In another embodiment, the security feature 16 is surrounded by a mosaic consisting of the surface elements 17 to 19 of the mosaic disclosed in EP 0 105 099A1. The optical effect structures 9 (such as optically, microscopically fine diffraction gratings, microscopically fine light scattering relief structures or planar mirror surfaces) at the surface portions 13 to 15 and at surface elements 17 to 19 ( 1) is formed in the interface 8 (FIG. 1).

Referring to Fig. 3, how the incident light 11 entering the interface 8 (Fig. 1) is reflected by the optical effect structure 9 and how it is deflected by a predetermined method will be described. Incident light 11 enters the optical effect structure 9 of the layer composite 1 at the diffraction surface 20, which is perpendicular to the surface of the layer composite 1 at the security member 2. And has a surface normal 21. The incident light 11 is composed of a plurality of beams of parallel light, and has an incident angle α with respect to the surface normal 21. When the optical effect structure 9 is a flat mirror surface having a parallel relationship with respect to the surface of the layer composite 1, the surface normal 21 and the direction of the reflected light 22 have a reflection angle β of −α. (Β = -α). When the optical effect structure 9 is one of the known gratings, the grating is incident light at various diffraction orders 23 to 25 determined according to the spatial frequency f of the grating. (11) is biased, and the grating vector representing the grating is assumed to be in the diffraction plane 20. The wavelength λ of the incident light 11 is deflected in various diffraction orders 23 to 25 determined by a predetermined angle. For example, the grating has a purple ray (λ = 380 nm) as a positive 26 first beam 23 and a negative beam 27 27. And the beam 28 of the negative second-order procedure 25 at the same time. The longer wavelength [lambda] optical element of the incident light 11 is emitted at an angle that includes a larger diffraction angle than the surface normal 21, for example, the red light ([lambda] = 700 nm) is represented by an arrow 29, 30, 31). The polychromatic incident light 11, which is the result of diffraction in the grating, fans out into a beam of light having various wavelengths λ of the incident light 11. For example, the visible region of the spectrum is a beam of purple light (arrows 26 or 27 or 28, respectively) and a beam of red light (arrows 29 or 30 or 31, respectively) at each diffraction order (23 or 24 or 25). Extends the range between. The light diffracted at the diffraction order of zero is the reflected light 22 reflected at the reflection angle β.

4 shows a diffraction grating 32 formed on surface elements 17 to 19 (FIG. 2), wherein the microscopically fine relief profile R (x, y) of the diffraction grating is, for example, a constant. It has a periodic profile cross section of a sinusoidal type having a profile height h and a spatial frequency f. The average relief of the diffraction grating 32 forms a central plane or a central surface 33, which is arranged parallel to the cover layer 4. Incident light 11 incident in parallel passes through the cover layer 4 and the shaping layer 5 and is deflected in the optical effect structure 9 (FIG. 1) of the diffraction grating 32. The parallel diffracted light beam 34 having the wavelength λ leaves the security member 2 in the viewing direction of the observer 35, and the incident light 11 in which the surface pattern 12 (FIG. 2) is incident in parallel. When illuminated by the observer, the observer sees the surface elements 17, 18, and 19 that are brightly colored.

In Fig. 5, the diffractive surface 20 becomes the plane of the figure. The diffractive structure S (x, y) is locally inclined with respect to the surface of the layer composite 1 in at least one of the surface portions 13-15 (FIG. 2) of the security feature 16 (FIG. 2). Or in the central plane 33 of the curved diffractive structure. The diffraction structure S (x, y) is a function of the coordinates x, y in the plane of the surface pattern 12 (FIG. 2), the plane of the surface pattern 12 being parallel to the surface of the layer composite 1 In addition, surface portions 13, 14, and 15 (FIG. 2) exist in the plane of the surface pattern 12. At each point P (x, y), the diffraction structure S (x, y) determines the spacing z with respect to the plane of the surface pattern 12, spaced parallel to the surface normal 21. do. In more general terms, the diffraction structure S (x, y) is a superposition function of the relief profile R (x, y) of the diffraction grating 32 (FIG. 4) and the clearly defined central plane 33. It is the sum of M (x, y). That is, S (x, y) = R (x, y) + M (x, y). As an example, the relief profile R (x, y) results in a periodic diffraction grating 32 having a profile of one of the known sinusoidal symmetrical or asymmetric serrated or square shapes.

In another embodiment, the microscopic fine relief profile R (x, y) of the diffractive structure S (x, y) is in a matt structure instead of the periodic diffraction grating 32. The mat structure is a microscopically microscopic and probabilistic structure having predetermined dispersion characteristics with respect to the incident light 11, and includes a predetermined direction as an anisotropic mat structure instead of the grating vector. The mat structure scatters the vertical incident light into a scattering cone having an axis of the reflected light 22 direction and having a divergence angle preset according to the scattering ability of the mat structure. The intensity of the scattered light, for example, is greatest in the axis of the cone, and decreases with distance from the axis of the cone, and the light deflected in the direction of the scatterer cones can still be perceived by the viewer. The cross section of the scattering cone perpendicular to the axis of the cone is symmetrical, in this case referred to as isotropic in the mat structure. If, on the contrary, the cross section is biased in a certain direction, ie the axis of the ellipse is deformed into an ellipse parallel to the particular direction, then the mat structure is called 'anisotropic'.

Because of the addition or subtraction overlap, the profile height h (FIG. 4) of the relief profile R (x, y) does not change in the region of the overlap function M (x, y). In other words, the relief profile R (x, y) follows the overlap function M (x, y). The explicitly defined overlapping function M (x, y) can be at least partially differentiated and at least partially curved. That is, ΔM (x, y) ≠ 0 periodically or aperiodically, and not a periodic trigonometric or square function. The periodic superposition function M (x, y) has a spatial frequency F of up to 20 lines / mm. For good visibility, the connecting section between two neighboring extremes of the superposition function M (x, y) is at least 0.025 mm long. The preferred value of the spatial frequency F is limited to a maximum of 10 lines / mm, and considering the spacing of neighboring extremes, the preferred value is at least 0.05 mm. Thus, the superposition function M (x, y) changes as a macroscopic function in a steady area compared to the relief profile R (x, y).

Line 36 (FIG. 2) is projected onto the plane of surface pattern 12 (FIG. 2) to form a section line of diffraction surface 20 with center plane 33. As shown in FIG. The superposition function M (x, y) takes the gradient 38 grad (M (x, y)) as a stable part on any point P (x, y) on the connection section parallel to the line 36. Have In general terms, when the observer 35 forms the optically effective diffractive surface 20, the gradient 38 refers to the component at the diffractive surface 20 of grad (M (x, y)). At any point of the surface portion 13, 14, 15, the diffraction grating 32 has a slope γ determined by the gradient 38 of the superposition function M (x, y).

Deformation of the central plane 33 results in a new and beneficial optical effect. The effect is, for example, on the diffraction characteristics at the intersections A, B, C with respect to the center plane 33 of the surface normal 21 and the surface normals 21 ′, 21 ″ along the line 36. The refraction of the incident light 11 and the diffracted light beam 34 at the interface of the reflected light 22 and the layer composite 1 are not shown for simplicity in FIG. 5 and are calculated here. At each intersection A, B, C, the slope γ is determined by the gradient 38. Normals 21 ', 21 ", the grating vector of the diffraction grating 32 (FIG. 4). And the viewing direction 39 of the observer 35 is arranged in the diffraction surface 20. The angle of incidence α (FIG. 3) between the white light 11 incident in parallel and the normals 21, 21 ', 21 "shown in dashed lines is changed according to the angle of inclination γ. The predetermined viewing direction of the observer 35 ( There is also a change in the wavelength [lambda] of the beam 34 of diffracted light refracted by 39. When the normal 21 'is inclined away from the observer 35, the beam of diffracted light 34 The wavelength is larger than when the normal 21 ″ is inclined towards the observer 35. In the example shown for illustrative purposes, from the perspective of the observer 35, the beam 34 of light diffracted in the region of the intersection point A is red (λ = 700 nm). The beam 34 of light diffracted in the region of the intersection point B is green yellow (λ = 550 nm), and the beam 34 of light diffracted in the region of the intersection point C is blue (λ = 400 nm). As shown in the example, the slope γ continues to change with respect to the gradient of the central plane 33, and the observer 35 is in full visible spectrum at the surface portions 13, 14, 15 along the line 36. The visible spectral color band extends above the surface portions 13, 14, 15 perpendicular to the line 36. Thus, the color band of the spectrum is applied at least 2 mm in length or more as the distance between the intersection point A and the intersection point C so that it can be recognized by the observer 35 at a distance of 30 cm. Outside of the visible spectrum, the surface of the surface portions 13, 14, 15 is gray with low light intensity. When the layer composite 1 is inclined with respect to the inclination axis 41 perpendicular to the plane of the figure shown in FIG. 3, the incident angle α changes. The visible color band of the spectrum is continuously shifted along the line 36 in the region of the superposition function M (x, y). In the case of the oblique movement, for example, in the clockwise direction with respect to the inclination axis 41 of the layer composite 1, the color of the beam 34 of light diffracted at the intersection A changes to greenish yellow, The color of the beam 34 of light diffracted at B) changes to blue, and the color of the beam 34 of light diffracted at the intersection C changes to purple. The change in the color of the diffracted light 34 is perceived by the observer 35 as the color band moves continuously with respect to the surface portions 13, 14 and 15.

The above considerations are also applicable for each diffraction order. Frequency and amplitude of the superposition function M (x, y) between the surface portions 13, 14, and 15, where at the surface portions 13, 14, and 15 how many color bands are simultaneously shown to the observer for how many diffraction orders. And the spatial frequency of the diffraction grating 32.

In another embodiment in which one of the mat structures is used instead of the diffraction grating 32, the observer 35 can see only bright white-gray bands in the direction of the reflected light 22. In the oblique movement, the bright white-grey band moves continuously like a color band with respect to the surface portions 13, 14, 15. In contrast to the color bands, the bright white-gray band is directed to the observer 35 irrespective of the scattering ability of the mat structure, even if the viewer's 35 viewing direction 39 is tilted relative to the diffractive plane 20. Can be seen. The term 'strip 40' (FIG. 6 (a)) here refers to both the color bands of the diffraction orders 23, 24 and 25 and the bright white-gray bands produced by the matte structure. It is used to.

Referring to FIG. 6A, the movement of the strip can be more easily recognized by the observer 35 (FIG. 5) based on the security feature 16. An identification mark 37 disposed on the surface portion 13, 14, 15, for example, on the central surface portion 14, and / or a predetermined boundary shape of the surface portion 13, 14, 15 is provided. It serves as a standard. Preferably, the criterion forms a preset observation condition that can be easily adjusted by the tilting motion of the layer composite 1 (FIG. 1), in which the strip 40 is positioned in a predetermined relationship relative to the criterion. Done. Preferably, in the region of the identification mark 37, the optical effect structure 9 (FIG. 1) of the interface 8 (FIG. 1) is an optical effect structure 9, a diffractive structure, a mirror surface, or a surface portion. It becomes the form of the light-scattering relief structure formed in the radiation of the surface pattern 12 of the relationship which matches (13, 14, 15). The light-absorbing agent printed on the security feature 16 can also be used as a reference for the movement of the strip 40, and the identification mark 37 can be made by a structured reflective layer.

In another embodiment of the security feature 16 shown in FIGS. 6A to 6C, the neighboring surface portions 13 and 15 engaging the central surface portion 14 on both sides function as mutual references. do. Neighboring surface portions 13 and 15 both have diffractive structures S ^* (x, y). In contrast to the diffractive structure S (x, y), the diffractive structure S ^* (x, y) is the difference RM between the relief function R (x, y) and the superposition function M (x, y). That is, S ^* (x, y) = R (x, y) -M (x, y). The color band produced by the diffractive structure S ^* (x, y) has a reversed color configuration with respect to the color band of the diffractive structure S (x, y), which uses a thick longitudinal edge to the strip 40. 6 (a). For good visibility of the optical effect without further assistance, the security feature 16 has a size of at least 5 mm, preferably at least 10 mm along the coordinate axis y or line 36. The size for the coordinate axis x is at least 0.25 mm, preferably at least 1 mm.

In the embodiment of the security feature 16 shown in FIGS. 6A to 6C, the elliptical surface portion 14 has a diffractive structure S (y) which depends only on the coordinate axis y, whereas only the coordinate axis y Surface portions 13 and 15 having a diffractive structure S ^* (y) which depend on extend to both sides of the elliptical surface portion 14 along the coordinate axis y. The superposition function M (y) is 0.5 · y ² · K, where K is the curvature of the central plane 33. The gradient 38 (FIG. 5) of the diffraction grating 32 (FIG. 4) and the predetermined direction of the grating vector or 'anisotropic' mat structure are oriented substantially parallel and non-parallel with respect to the direction of the axis y. ).

In general terms, the azimuth angle of the grating vector, or the azimuth angle φ in the predetermined direction of the mat structure, is related to the gradient plane determined by the gradient 38 and the surface normal 21. Preferred values of the azimuth angle φ are 0 ° and 90 °. In this regard, in order for the predetermined direction of the grid vector or the mat structure to appear substantially parallel or perpendicular to the gradient plane in that region, the azimuth deviation tolerance of the predetermined direction of the grid vector or the mat structure is in accordance with the desired value. Δφ = ± 20 ° respectively. The azimuth angle φ itself is not limited to any particular value.

In each case, the smaller the curvature K, the strip 40 in the direction of the arrow for the unit angle of the rotational movement about the inclined axis 41 (no part number is indicated in FIGS. 6A to 6C). ) The speed of movement becomes greater. In order to clearly explain the movement effect, the strip 40 is shown by arrows in FIGS. 6 (a) to 6 (c). The width of the strip 40 in the direction of the arrow without the member number is irrelevant to the diffractive structure S (y). In particular, in the case of a collar band, the spectral collar shape extends over the major portion of the surface portions 13, 14, 15 so that the movement of the strip 40 is dependent on the movement of a portion of the visible spectrum, for example the red collar band. Observed on the basis of

6B shows the security feature 16 with the two outer surface portions 13, 15 and the strips 40 of the central surface portion 14 positioned on a line parallel to the inclination axis 41. Shows the state after rotating at a predetermined inclination angle with respect to the inclination axis 41. The predetermined inclination angle is determined by the selection of the superposition function M (x, y). In the embodiment of), only when the strip 40 has a predetermined position in the security feature 16, i.e., only when the observer 35 sees the security element 2 under an observation condition determined by the predetermined inclination angle. This preset pattern is shown on the surface pattern 12.

In FIG. 6C, after further rotational movement about the tilt axis 41, the strips 40 on the security feature 16 are again far from each other as shown by the arrows in FIG. 6C. Move to lose

In another embodiment, a neighboring arrangement of the central surface portion 14 and one of the two surface portions 13, 15 is also sufficient for the security feature 16.

FIG. 7 is a cross-sectional view taken along line 36 (FIG. 2), for example in the region of the surface portion 4 (FIG. 2), for the layer composite 1. The structure height H _St (FIG. 1) of the diffractive structure S (x; y) is limited so that the layer composite 1 does not become too thick so that the production or use of the layer composite 1 is not difficult. Although not drawn in real size in FIG. 7, the superposition function M (y) = 0.5 · y ² · K is shown in the drawing, for example, and the height of the layered composite is indicated on the left coordinate axis z. At any point P (x, y) of the surface portion 14, the value z = M (x, y) is limited to a preset change amount value H = z ₁ -z ₀ . As soon as the value z ₁ = M (P _j ) is reached at either point P ₁ , P ₂ , ..., P _n for j = 1, 2, ..., n, the discontinuous position It occurs at M (y), and at the discontinuous position, on the side far from the point P ₀ , the value of the superposition function M (y) decreases by the value H by the height z ₀ , respectively. That is, the value of the superposition function M (x, y) used in the diffraction structure S (x; y) becomes a function value of Equation 1 below.

z = {M (x; y) + C (x; y)} modulo value H-C (x; y)

In this regard, the function C (x; y) is limited to a range of predetermined values, for example half the value of the structure height H _St. Function {M (x; y) + C (x; y)} The dislocation position of the modulo value H-C (x; y) is created for technical reasons, which is the nesting function M It is not calculated as an extreme for (x; y). Equivalently, for a given shape, the value for H is locally smaller. In the embodiment of the diffraction structure S (x; y), the locally varying value H does not exceed the preset value from the range between 40 μm and 300 μm between the two sequential discrete positions P _n. Is determined by the fact.

In the surface portions 13, 14, and 15 (FIG. 2), the diffraction structure S (x, y) extends on both sides of the coordinate axis z, not only on the right side of the coordinate axis z, as shown in FIG. Because of the overlapping effect, the structure height H _St is the sum of the value H and the profile height h (FIG. 4), which is equal to the value of the diffractive structure S (x, y) at the point P (x; y). The structure height H _St is preferably smaller than 40 μm, more preferably smaller than 5 μm. The value H of the superposition function M (x, y) is limited to values smaller than 30 μm, preferably in the range of H = 0.5 μm and H = 4 μm. On a microscopic scale, the mat structure has a fine relief structural element that determines scattering capacity, the fine relief structural element having, for example, a mean roughness value (R _a ), _a correlation length. It can only be expressed by statistical parameters such as (l _c ), in which the average roughness value (R _a ) is in the range between 200 nm and 5 μm, with preferred values of R _a = 150 nm and R _a = 1.5 μm. Is a value in the range between. On the other hand, the correlation length l _{c in} at least one direction is in the range between 300 nm and 300 μm, and a preferable value is in the range between l _c = 500 nm and l _c = 100 μm. In the 'isotropic' mat structure, the statistical parameters are independent of the preferred direction, whereas in the 'anisotropic' mat structure, the relief elements are oriented with a correlation length l _c perpendicular to the preferred direction. The profile height h of the diffraction grating 32 (FIG. 4) is h 0.05 μm and h A value is in the range of = 5 μm, with a preferred value being in the narrower range h = 0.6 ± 0.5 μm. The spatial frequency f of the diffraction grating 32 is selected within the range between f = 300 lines / mm and f = 3300 lines / mm. From about 2400 lines / mm the diffracted light 34 (FIG. 5) can only be observed at a diffraction order of zero, that is to say in the direction of the reflected light 22 (FIG. 5).

Another example of the nested function M (x, y) is

M (x, y) = 0.5 · (x ² + y ² ) · K, M (x, y) = a · {1 + sin (2πF _x · x) sin (2πF _y · y)}, M ( x, y) = a · x 1.5 + b · x, M (x, y) = a · {1 + sin (2πF xy · y)}

Here, F _x and F _y are the spatial frequencies F of the superposition function M (x, y) in the coordinate axes x and y directions, respectively. In another embodiment of the security feature 16, the overlap function M (x, y) is periodically synthesized from a predetermined portion of another function and has one or more periods along the line 36.

In FIG. 8A, the superposition function M (x, y) = 0.5 · (x ² + y ² ) · K, i.e., the sphere portion and the relief structure R (x, y), i.e. the 'isotropic' mat structure In the surface portion 14, a diffraction structure S (x, y) (Fig. 7) is made, for example, a diffraction structure S (x, y) having a circular edge is made. In daylight, the observer 35 sees a white-gray spot 42 in contrast to the dark gray background 43, through the visual direction 39 (FIG. 5), with the identification mark 37. In relation, the position of the spot 42 in the surface portion 14 and the contrast between the spot 42 and the background 43 depend on the visual direction (viewing direction) 39. The range of the spot 42 is determined by the curvature of the superposition function M (x, y) and the scattering ability of the mat structure. In order that the spot 42 is located in the identification mark 37, that is, for example, in the identification mark 37 arranged at the center of the surface portion 14 with a circular edge, the security member 2 is an example. For example, it is inclined with respect to the inclined axis 41 (FIG. 5) and / or rotated about the surface normal 21 (FIG. 5), and is oriented in the predetermined viewing direction 39.

9 shows the light-diffraction effect of the diffractive structure S (x, y) in the diffractive surface 20. The relief structure R (x, y) (FIG. 4) is a diffraction grating 32 (FIG. 4) having a spatial frequency smaller than 2400 lines / mm and a sinusoidal profile, for example. The grating vector of the relief structure R (x, y) is in the diffraction plane 20. The superposition function M (x, y) in the surface portions 13, 14, 15 (FIG. 2) of the security feature 16 is determined by the effect of the diffractive structure S (x, y), where each predetermined The light 11 incident on the layer composite 1 at the observation angles of + θ and −θ is refracted by the positive diffraction order 23 (FIG. 3) or the negative diffraction order 24 (FIG. 3), respectively. In the diffraction surface 20, the first beam 44 having the wavelength λ ₁ has an observation angle θ with respect to the incident light 11, and the second beam 45 having the wavelength λ ₂ is observed with respect to the incident light 11. Has angle -θ. The observer 35 (FIG. 5) recognizes the surface portions 13, 14 and 15 in the color of the wavelength λ ₁ at the observation angle θ. After the layer composite 1 is rotated 180 ° in that plane, the surface portions 13, 14, and 15 appear in the color of the wavelength λ ₂ at the viewing angle -θ at the observer 35. If the central plane 33 includes a local tilt γ = 0 °, the wavelengths λ ₁ and λ ₂ are not different. For other values of local gradient γ, the wavelengths λ ₁ and λ ₂ are different. The normal 21 'to the inclined central plane 33, shown in dashed lines in the figure, has an angle α with respect to the incident light 11, where α = -β = -γ. The first beam 44 and the normal 21 'have a diffraction angle ξ ₁ , whereas the second beam 45 and the normal 21 ′ have a diffraction angle ξ ₂ .

Since ξ _k = asin (sin α + m _k λ _k · f) and α = γ, the relationship between the first two diffraction orders 23, 24, that is, the relationship of m _k = ± 1, Same as

f · (λ ₁ + λ ₂ ) = 2sin (θ) cos (γ)

In Equation 2 above, for a preset value of observation angle θ and spatial frequency f, the sum of the _two wavelengths λ ₁ and λ ₂ of the beams 44, 45 is proportional to the cosine of the local tilt angle γ.

Equation 2 is easily derived for another order m. The order M and the observation angle θ for a given observable color are determined by the spatial frequency f.

10A and 10B, an embodiment of a security feature 16 is shown, in which the security member 2 is rotated 180 ° in its plane relative to the security member 2 shown in FIG. 10B. Diffractive surface 20 (FIG. 9) is shown by line 36. 10A and 10B, the security feature 16 has three surface portions 13, 14, and 15 with diffractive structure S (x, y) = R (x, y) + M (x, y). In the three surface portions 13, 14, and 15, the diffraction structure S (x, y) is local to the spatial frequency f of the relief profile R (x, y) and the superposition function M (x, y). For the slope γ, it is distinguished by the values determined by Equation 2 above. The background field 46 is connected to at least one surface portion 13, 14, 15, the background field 46 having the same relief profile R (x) as the spatial frequency f specified for the background field 46. has a diffraction grating 32 (Fig. 4) with y. The lattice vector of the relief profile R (x, y) is oriented in parallel with the line 36 at the surface portions 13, 14, 15 and the background field 46. When the white incident light 11 (FIG. 9) is irradiated perpendicularly to the security member 2, the surface portions 13, 14 and 15 and the background field 46 are in the direction shown in FIG. 10A at the observation angle + θ. The same color within the security feature 16, which turns out to be a uniform color without contrast (contrast) with respect to the observer 35 (FIG. 5). For example, the deflected first beam 44 (FIG. 9) is, for example, a wavelength λ ₁ of 680 nm (red). In the direction shown in FIG. 10B, the entire security feature 16 is observed at the observation angle −θ. For example, the first surface portion 13 is revealed by the first beam 45 (FIG. 9) of wavelength lambda ₂ , for example, lambda ₂ = 570 nm (yellow), and the second surface portion 14 Is revealed by the second beam 45 of wavelength λ ₃ , for example λ ₃ = 510 nm (green), and the third surface portion 15 is wavelength λ ₄ , for example λ ₄ = 400 nm (blue). Is revealed by the second beam 45. In the background field 46 of the central plane 33 (FIG. 9) of the diffraction grating 32 (FIG. 4) with the inclination γ (FIG. 9) having a value of γ = 0, the second beam 45 is for reasons of symmetry. ) Also has a wavelength λ ₁ . In other words, the background field 46 also emits red. The advantage of this embodiment is that it shows the prominent optical properties of the security feature 16, where the color contrast is seen in one preset direction of the security element 2 and with respect to the surface normal 21 (FIG. 3). After turning (2) 180 °, the color contrast changes or disappears. Thus, the security feature 16 serves to create a preset orientation of the security member 2 with the security feature 16 on which a holographic copy can be made.

It is merely illustrative for the sake of simplicity that a uniform color, i. E. A constant gradient γ can be applied in each surface portion 13, 14, 15, for example. In general terms, since the surface portions 13, 14 and 15 have a portion from the superposition function M (x, y), the inclination γ in the surface portions 13, 14 and 15 is continuously in the preset direction. And the wavelengths of the second beam 45 originate from both regions of the wavelength λ _k . Instead of simply limiting the surface portions 13, 14, 15, the plurality of surface portions 13, 14, 15 arranged in the background field 46 form logos, letters, and the like.

In Fig. 11, the diffractive structure S (x, y) has more complicated characteristics. The superposition function M (x, y) is symmetric, partly steady, and periodic, whose value varies along the coordinate axis x by the relation z = M (x, y), while M (x, y) has a constant value z along the coordinate axis y. For example, the rectangular surface portions 13, 14, 15 (FIG. 10) are narrow in their longitudinal direction oriented parallel to the coordinate axis x and having a side surface in a direction parallel to the coordinate axis y and having a width b. It is divided into the dividing surface 47.

Each period 1 / F _x of the overlapping function M (x; y) is expanded with respect to the number t of the dividing surfaces 47. For example, the number t is a value in the range between 5 and 10. The width b is 10 mu m or more, and the diffractive structure S (x, y) is too small to be defined on the dividing surface 47.

The diffractive structure S (x, y) of the neighboring dividing surface 47 is at the relief profile R (x, y) and the summands of the portion of the overlapping function M (x, y) associated with the dividing surface 47. There is a difference. The relief profile R _i (x, y) of the i-th dividing surface 47 is equal to two of the neighboring dividing surfaces 47 in at least one lattice parameter such as azimuth, spatial frequency, profile height h (FIG. 4), and the like. Relief profiles R _{i + 1} (x, y) and R _i-1 (x, y). If each spatial frequency F _x and F _y is 2.5 lines / mm to 10 lines / mm, the observer 35 (FIG. 5) no longer has a surface portion 13 by the period of the superposition function M (x, y). , 14, 15) can not be visually recognized. Subdivision and occupation with diffractive structure S (x, y) are repeated for each period of superposition function M (x, y). In another embodiment of the security feature 16, the relief profile R (x, y) changes continuously as a function of the phase angle of the periodic overlapping function M (x, y).

The diffractive structure S (x, y) shown in FIG. 11 is used in the embodiment of the security feature 16 shown in FIGS. 12A and 12B, in which the security axis 16 is inclined axis 41 parallel to the coordinate axis y. When inclined with respect to), white light 11 exhibits a novel optical effect on irradiation. The security feature 16 comprises a triangular first surface portion 14 arranged in a rectangular second surface portion 13. In the first surface portion 14, the diffraction structure S (x, y) is characterized in that the spatial frequency f of the relief profile R (x, y) is in the coordinate axis x direction within each period of the superposition function M (x, y). Divided by a predetermined spatial frequency range δf, stepwise or continuously, wherein the spatial frequency f _i at the i-th division plane 47 is the preceding division plane, i.e., the i-1 th division plane 47 ( It is larger than the spatial frequency f _i-1 in FIG. 7). Thus, in each period, the first partition 47 comprises a spatial frequency f of the value f _A. For the dividing surface 47 at the minimum of the period, the spatial frequency f = f _M , and for the dividing surface 47 at the end of the period, the spatial frequency f = f _E , where f _A <f _M <f _E And δf = f _E -f _A. In the second surface portion 13, the diffraction structure S (x, y) is characterized in that the spatial frequency f of the relief profile R (x, y) is in the coordinate axis x direction within each period of the superposition function M (x, y). It is distinguished by decreasing stepwise or continuously from one dividing surface 47 to the next. In an embodiment, for example, the diffractive structure S ^** (x, y) = R (−x, y) + M (−x, y) of the second surface portion 13 is the first surface portion 14. Is the diffraction structure S (x, y), which is the symmetrical relationship with respect to the plane defined by the coordinate axis y, z. Lines 36 (FIG. 11) of the grating vector and diffraction surface 20 (FIG. 9) are oriented in a substantially parallel relationship with respect to the inclination axis 41 at the surface portions 13 and 14. Gradient 38 is substantially parallel to the plane defined by coordinate axes x, z.

In FIG. 12A, the security feature 16 is in the xy plane defined by coordinate axes x, y, with the visual direction 39 (FIG. 5) perpendicular to the coordinate axis x. In the case of the vertical white incident light 11, the dividing surfaces 47 are illuminated at the minimum region of the superposition function M (x, y). In the diffractive structures S (x, y) and S ^** (x, y), the divided surfaces 47 have the same relief profile R (x, y) and the same inclination γ ≒ 0 °, so that two surface portions ( A beam of light 34 (FIG. 5) diffracted in the viewing direction 39 at 13, 15 is emitted in the same visible spectral range (e.g. green), thus the first surface on the security feature 16 The color contrast between the portion 14 and the second surface portion 13 disappears. When the security feature 16 is inclined with respect to the inclination axis 41, as shown in FIG. 12B, the color contrast becomes sharper as the inclination angle increases. When the security feature is tilted to the left, the first surface portion 14 becomes effective, with the partition surface 47 (Fig. 11) having a spatial frequency f of the relief profile R (x, y) having a value smaller than f _M. Is indicated in the red direction. The color of the second surface portion 14 is displayed in the blue direction while the dividing surface 47 whose spatial frequency f of the relief profile R (x, y) has a value larger than f _M becomes effective. In FIG. 12C, the security feature 16 is tilted to the right from the position shown in FIG. 12A with respect to the tilt axis 41. When tilted to the right, color contrast is remarkable while having mutually changed colors. As the dividing surface 47 whose spatial frequency f of the relief profile R (x, y) is larger than f _M becomes effective, the color of the first surface portion 14 shifts in the blue direction, and the diffraction structure S ^** The color of the second surface portion 12 becomes effective as the dividing surface 47 (FIG. 11) in which the spatial frequency f of the relief profile R (x, y) of (x, y) decreases with respect to f _M becomes effective. Will move to red.

In another embodiment of the diffractive structure S (x, y) shown in FIG. 11, the relief profile R (x, y) in the dividing plane 47 of each period 1 / F _x has the same spatial frequency, The relief profile R (x, y) is distinguished from the other dividing planes 47 by the azimuth angle φ of the grid vector with respect to the coordinate axis y. Within the period 1 / F _x the azimuth angle φ changes stepwise or continuously, for example, within the range of φ ≒ 0 ° to δφ = ± 40 °. The azimuth angle φ is selected according to the local inclination γ (FIG. 5) of the central plane 33 (FIG. 5) in the range of δφ, on the other hand, at all inclination angles (FIG. 12B and 12C) of the inclined axis 41. The diffractive structure S (x, y) of one surface portion 14 (FIG. 12A) shows a beam 34 (FIG. 5) of diffracted light in a color range, for example, a green range, preset by the spatial frequency f. In the second surface portion 13 (FIG. 12A), which emits in the viewing direction 39 (FIG. 5), on the other hand, the mirror diffraction structure S ^** (x, y) is formed, only one preset Only at the inclination angle the light is emitted in a predetermined color, for example a mixed color resulting from the green range. At other inclination angles, the second surface portion 13 is dark grey. For example, for the azimuth range δφ = ± 20 °, the green range extends from the wavelength λ = 530 nm (φ ≒ 0 °) to the wavelength λ = 564 nm.

In Fig. 13, the superposition function M (x, y) used in the diffraction structure S (x, y) is an asymmetric function in the x-axis direction. The overlapping function M (x, y) periodically rises from the minimum value to the maximum value within a period 1 / F _x , for example, a function y = const × x ^1.5 . The spatial frequencies F _x and F _y are each in a range of at least 2.5 lines / mm and inclusive of 10 lines / mm. The discontinuities that occur due to the operation modulo value H (FIG. 7) are not shown here. As described above, an 'anisotropic' mat structure having a predetermined direction substantially parallel to the coordinate axis x is used as the relief profile R (x, y). The incident light 11 (FIG. 5) is basically scattered in parallel with the coordinate axis y. A diffractive structure in which S (x, y) = R (x, y) + M (x, y) is formed in the first surface portion 14 (FIG. 12A), and S ^** (x, y) = R ( A diffractive structure of -x, y) + M (-x, y) is formed in the second surface portion 13 (Fig. 12A). The optical effect of the security feature 16 is described with reference to FIG. 12A with incident light 11 (FIG. 9) with respect to the xy plane. When the security feature 16 is in the xy plane, the incident light 11 having a high intensity is scattered by the matte structure in the minimum region of the superposition function M (x, y), and the diffractive structures S (x, y), S ^** The scattering effect of the other dividing planes 47 of (x, y) is ignored. The light backscattered by the surface portions 13, 14, 15 includes the color of the incident light 11 and has the same surface brightness within the two surface portions 13, 14, so that the two surface portions ( 13, 14) no contrast can be seen. In FIG. 12B, the incident light 11 (FIG. 5) enters the incident feature α at the security feature 16 which is tilted to the left about the tilt axis 41. The incident light 11 (FIG. 5) is only continuously scattered at the second surface portion 13. Under these lighting conditions, the surface brightness of the first surface portion 14 is of an order of magnitude less than the second surface portion 13, so that the first surface portion 14 is formed of the second surface portion 13. It appears as a dark side to light. In FIG. 12C, the security feature 16 is inclined to the right, in which case the surface brightness of the two surface portions 13, 14 are exchanged with each other.

In FIGS. 12A to 12C, instead of one triangular first surface portion 14, it is also possible to arrange a plurality of first surface portions 14, such as a logo, letters, or the like, on the second surface portion 13.

In another embodiment, instead of a simple mathematical function, a relief image employed in coins and medals may be used as the at least partially steady superposition function M (x, y) in the diffractive structure S (x, y). Here, the relief profile R (x, y) is preferably an 'isotropic' mat structure. In this embodiment, the observer of the security member 2 is impressed with a three-dimensional image with a characterized surface structure. When the security member 2 is rotated and tilted, the brightness distribution in the image changes as expected in relation to the actual relief image. However, the projected element does not create any shade.

Within the scope not departing from the spirit of the present invention, all diffractive structures S are limited to the height value H _St as their structure height is described with reference to FIG. The relief profile R (x, y) and superposition function M (x, y) used in the specific embodiments described above may be combined to provide other diffractive structures S (x, y) if necessary.

The use of the security feature 16 in the security member 2 has the advantage that an effective barrier can be established against attempts to holographically copy the security member 2. In holographic copying, positional movement or color shift on the surface of the security feature 16 can only be recognized in a modified form.

The present invention relates to a security element.

Claims (17)

And a layered composite (1) having a microscopic microscopic optically effective structure (9) of the surface pattern (12), the optically effective structure (9) between the layers (5; 6) of the layered composite (1). Engraved in, the optical effect structure 9 is provided in the surface portions 13; 14; 15 of the security feature 16 in the plane of the surface pattern 12 defined by coordinate axes x, y. In the security member (2) formed by the reflective interface (8) between the layers (5; 6), The at least one surface portion 13; 14; 15 having a size larger than 0.4 mm is a diffractive structure formed by adding or subtracting an overlapping function M defining a macroscopic structure to the microscopic fine relief profile R. Has (S; S ^* ; S ^** ), The superposition function (M), relief profile (R) and diffraction structure (S; S ^* ; S ^** ) define a light-diffraction or light-scattering optical effect structure (9), which optical effect structure Along the function (M) will have a preset relief profile (R), The at least partially steady superposition function (M) has a gradient in at least some intervals but is not a periodic triangular or square function, and is characterized in that it changes slowly compared to the relief profile (R). The method according to claim 1, The security feature 16; 16 ′ has at least two adjacent surface portions 13; 14; 15, The first diffractive structure S is formed on the first surface portion 14, and the second diffractive structure S ^* ; S ^** which is different from the first diffractive structure S is the second surface portion 13; 15. ), The predetermined direction or lattice vector of the first relief profile R of the first surface portion 14 and the predetermined direction or lattice vector of the second relief profile R of the second surface portions 13 and 15 are substantially Security member characterized in that the parallel direction. The method according to claim 1 or 2, And said superposition function (M) is an asymmetrical and partially steady periodic function having a spatial frequency (F) of at most 5 lines / mm. The method according to claim 1 or 2, And said superposition function (M) defines a relief image. The method according to any one of claims 1 to 3, In the diffraction structure S; S ^* ; S ^** , the predetermined direction and the lattice vector of the relief profile R are the surface normal 21 and the superposition function M perpendicular to the plane of the layer composite 1. Security member, characterized in that substantially parallel to the gradient surface determined by the gradient (38) of. The method according to any one of claims 1 to 5, In the first surface portion 14, the first diffractive structure S is formed by the sum of the relief profile R and the overlapping function M, The second diffractive structure (S ^* ) in the second surface portion (13; 15) is characterized in that it consists of the difference (RM) between the relief profile (R) and the superposition function (M). The method according to any one of claims 1 to 4, In the diffractive structure S; S ^* ; S ^** , the predetermined direction of the relief profile R and the lattice vector are obtained by the superposition of the surface normal 21 and the superposition function M perpendicular to the plane of the layer composite 1. Security member, characterized in that substantially perpendicular to the gradient surface determined by the gradient (38). The method according to any one of claims 2, 3, and 7, In the first surface portion 14, the first diffractive structure S is formed by the sum of the relief profile R and the overlapping function M, The second diffractive structure (S ^** ) in the second surface portion (13; 15) is a security member, characterized in that the first diffractive structure (S) of the mirror reflection. The method according to any one of claims 1 to 8, At least one identification mark 37 is disposed on at least one of the surface portions 13; 14; 15, The identification mark 37 forms a preset visual direction 39, At least one stiffer 40 or spot 42 is illuminated by the diffracted light 34 and moved on the lighted surface portions 13; 14; 15 by tilting or rotating the security feature 16. Security member characterized in that is directed toward the identification mark (37). The method according to any one of claims 1 to 9, In at least one surface portion 13; 14; 15, the diffractive structure S is the sum of the superposition function M and the diffractive structure 32, The diffraction structure 32 is represented by a relief profile R and has a spatial frequency f, The superposition function M has a local gradient γ, and when the white light 11 is irradiated vertically, the light 34 diffracted at the surface portions 13; 14; 15 is incident on the incident light 11. Deflected at a predetermined symmetrical observation angle (+ θ; −θ) with respect to the first beam 44 having a first wavelength λ ₁ at the observation angle (+ θ) A second beam 45 having a second wavelength λ ₂ at another observation angle (−θ), And for a predetermined observation angle θ and a predetermined spatial frequency f, the sum of the two wavelengths λ ₁ ; λ ₂ is proportional to the cosine of the local tilt. The method according to claim 10, The surface portions 13; 14; 15 are connected to the background field 46 of the security feature 16, Along with the relief profile R, the diffraction grating 32 is formed with a background field 46, The spatial frequency 32 of the diffraction grating 32 is a value such that the first beam 44 and the second beam 45 have a first wavelength λ ₁ at an observation angle (+ θ; −θ). Security member. The method according to any one of claims 1 to 3, In each period of the superposition function M, the spatial frequency f of the azimuth angle φ and / or relief profile R is continuous in the dividing plane 46 or continuously within a preset azimuth range δφ. Or according to a local gradient γ of the superposition function M within a preset spatial frequency range δf. The method according to any one of claims 1 to 12, Relief profile (R) is a security member, characterized in that the diffraction grating 32 having a spatial frequency (f) greater than 300 lines / mm. The method according to any one of claims 1 to 12, Relief profile (R) is a security member, characterized in that the mat structure. The method according to any one of claims 1 to 14, Security member, characterized in that the neighboring extremes of the overlapping function (M) in the surface portion (13; 14; 15) are spaced at least 0.025 mm apart from each other. The method according to any one of claims 1 to 15, The diffractive structure (S; S ^* ; S ^** ) is limited to the structural height (H _St ) of less than 40㎛, Superposition function (M) is limited to the change value (H) less than 30㎛, The value z of the superposition function M used in the diffractive structure S; S ^* ; S ^** is equal to the modulo value H − − {M (x; y) + C (x; y)} Same as C (x; y), And the function C (x, y) is limited to half of the structure height H _St. The method according to any one of claims 1 to 16, The surface elements 17; 18; 19 having the optical effect structure 9 form part of the surface pattern 12, At least one of the surface elements (17; 18; 19) is connected to the security feature (16).