HU208279B - Surface pattern of variable optical effect - Google Patents

Abstract

The surface is pattern is divided into a rectangular matrix of individual fields (6) containing diffraction elements (8) having a spatial line frequency of more than 10 lines per mm. Each field (6) has a width and length of less than 0.3 mm and is divided into sections (7) each used to represent a respective pixel of the graphical image (3), having a relief structure determined by the optical parameters of the image. - Pref. at least one relief structure profile for the diffraction elements (8) is asymmetrical with the diffraction elements (8) having an azimuth angle of between 0 and 360 degrees.

Description

The present invention relates to a variable optical surface pattern comprising more than one planar drawing.

Variable optical surface samples are used for various purposes. Variable optical surface patterns created by microscopic relief patterns are used, for example, to protect securities against counterfeiting and to identify and identify various objects, in particular certificates, documents, securities, various means of payment and other valuables.

Embossed relief patterns with an optically effective outer surface result in deflection of the internal light rays in a defined reflection direction. The light deflection properties of the relief patterns are determined, among other things, by the spatial density of the relief pattern elements (line number / mm), profile shape, depth, and azimuthal location on the substrate. For example, there are known relief patterns whose cross-sectional profile corresponds to known periodic functions of optically effective frequency (spatial density greater than 10 lines / mm) along the wavelength of visible light. Embossed patterns with a cross-sectional profile formed according to non-periodic functions are also used, for example, to create matt optic surfaces. The depth of relief (the "amplitude" of the cross-section profile) is usually between 50 nm and 10,000 nm.

The light bending properties of various relief patterns can be found in R. Petit, Electromagnetic Theory of Gratings (Springer Verlag, Berlin Heidelberg New York 1980).

Such embossing patterns can be produced relatively simply and at low cost, for example, in a thermoplastic plastic layer with a heated embossing stamp, which also carries the negative of a security feature, galvanically stamped from a master piece, as disclosed in CH-PS 594 936.

Published Swiss Patent Application Serial No. 00805 / 88-4 discloses a variable optical surface pattern divided into lattice elements comprising active optical active light refractive elements having a spatial density of at least 10 lines / mm, comprising a planar representation of a planar pattern. implemented.

US-PS 4094575 discloses a method for forming a relief pattern on a hologram. The embossing pattern thus created can be stamped and copied into a plastic film. These relief patterns are difficult to recognize in certain forms of illumination, such as surface illumination such as fluorescent light.

SUMMARY OF THE INVENTION The object of the present invention is to provide a variable optical effect surface pattern which provides at least two different planar views which are viewed from specific directions and where the reality of the relief pattern is optically more readily detectable to a less experienced observer in natural or artificial light.

SUMMARY OF THE INVENTION This object is solved by providing a variable optical surface pattern divided into a number of lattice elements M (greater than M 1) comprising active optical elements having a spatial density of at least 10 lines / mm, which provides a planar representation. forming relief patterns according to the invention

- each grille shall have a maximum dimension of less than 0,3 mm,

- the lattice elements comprise N (integers greater than N 1) surface elements,

- each surface element has a light-bending element,

- the light-bending elements and the surface elements carrying them are assigned to each of the various figures N, and

the light-bending elements, such as the relief patterns they produce, are formed according to the surface portion to which they belong.

The variable optical surface design according to the invention thus comprises, by means of the proposed design, N figures which can be perceived by the naked eye from different viewing angles.

In the variable optical effect surface sample according to the invention, the light bending elements implementing the relief patterns preferably have at least one asymmetric cross-sectional profile and each light bending element within a lattice element has a predetermined angle between 0 ° and 360 °.

The lattice elements are preferably in the form of a regular rectangle, rectangle or parallelogram, the maximum diameter of the rectangle being not more than 0.3 mm.

Within the lattice element, the relative size of the reflecting surfaces of the light-bending elements corresponds to the relative luminance values predetermined for each figure in the lattice element.

Preferably, the relative degree of light bending of the luminous elements within the lattice element corresponds to predetermined relative luminance values for each lattice element.

According to the invention, preferably all the grid elements have the same size surface elements.

The free surface portions not occupied by the light-bending element within the surface elements preferably have a matt optical effect surface design.

For example, N in the variable optical surface pattern according to the invention is represented by N in different views. The figure N can also be the same view of the same object under different illumination conditions. depicted along directions.

The figures may also be raster photographs of a variable optical surface pattern of the present invention. The grid elements of the surface portions of the figures here have at least two luminosities! degree.

HU 208 279 Β

Preferably, the number of drawings in the variable optical surface pattern of the present invention is even, and there may be one or more stereoscopic pairs between the drawings. In such a design, a three-dimensional view of the depicted object can be seen from a given viewing angle.

The variable optical surface pattern of the present invention may also be part of a larger planar design. In this case, the contour of the surface pattern is partially or completely surrounded by another surface pattern.

The surface sample of the present invention is preferably molded into a support layer. The other side of the support layer may optionally be provided with an adhesive surface.

The invention will now be described with reference to the drawing. In the drawing:

Figure 1 is a schematic diagram of an exemplary embodiment of a variable optical surface design according to the invention, with reference to the figure;

Figure 2 shows a structural diagram of a lattice element of a surface sample according to the invention.

As shown in Figure 1, the surface pattern according to the invention is formed on the surface of a support layer (4) arranged on the surface of the object (5). The surface pattern (1) is delimited by a contour, which in this example defines a rectangle. The surface pattern comprises figures (3), of which Figure 1 shows a view of the house shown in a given direction. For example, the object (5) may be a security on which the surface pattern according to the invention serves as a security and / or identification symbol.

The surface pattern, and in particular Figure 3, is divided into surface portions (2). In Figure (3), the surface members (2) in our example represent the roof, the wall of the house and the front door. The surface portions (2) are divided into lattice elements (6). In this example, the lattice elements (6) are all of a congruent regular rectangular shape.

The exemplary surface pattern is subdivided into M lattice elements (6), where M 1 is an integer. For more graphically demanding surface patterns, the area delimited by the outline (1) should be divided into a plurality of grid elements (6), so that the grid elements (6) are not disturbingly perceptible to the naked eye at normal reading distance (about 30 cm). The shape of the lattice elements (6) can be arbitrary, but it is preferable to choose a regular shape, such as the aforementioned regular rectangle (square, rectangle, parallelogram) or circle. An essential feature of the invention is that the maximum size of the lattice elements (6) - the largest diagonal of the rectangle, the diameter of the circle, etc. - must not be larger than 0,3 mm. Thus, assuming a square surface pattern of 12 mm side length, the number of lattice elements (6) is greater than 1600.

The lattice elements (6) comprise at least two surface elements (7). Figure 2 shows an exemplary lattice element (6) comprising surface elements (7a, 7b, 7c, 7d, 7e and 7f). The surface elements (7a-7f) are coincident and have a parallelogram shape. In contrast, the lattice elements (6) shown in Figure 1 comprise four rectangular surface elements. The surface elements (7) are, in principle, of any shape, but are preferably of uniform, regular shape, for example triangular, rectangular or hexagonal, allowing complete coverage of the lattice elements (6).

The surface elements (7) comprise a light bending element (8). The light bending elements (8) provide relief patterns (9) of different microscopic sizes. The light-bending elements (8) have a spatial density ("frequency") of at least 100 lines / mm. The light bending elements (8) deflect the rays from the incident light direction indicated by the arrow (10) in the manner defined by the surface of the relief pattern (9).

For the sake of illustration, a schematic intersection surface is shown along the lower shorter side of the lattice element (6). The light-bending elements (8), such as the relief patterns (9), are preferably stamped on the surface of the support layer (4) with a mold. The outer surface of the relief pattern (9) is coated with a protective layer (11). The intermediate layer between the protective layer (11) and the relief pattern (9) embossed in the support layer (4) acts as an optical layer. If both the protective layer (11) and the supporting layer (4) are made of a transparent material, the surface pattern is visible when the refractive indices of the protective layer (11) and the supporting layer (4) are different. The difference between the refractive indices in the passage from the protective layer (22) to the support layer (4) behaves as an optical layer.

If the optical layer is a separate layer, such as a thin, reflective metal layer, preferably aluminum, gold, nickel, silver, etc., applied before the embossing pattern (9) is pressed. -, the surface pattern is visible by reflection through the protective layer (11). The bending elements (8) reflect the incident light rays indicated by the arrow (10) at high intensity after bending.

The backing layer (4) can also be applied to the surface of opaque objects (5), resulting in an increased application of the surface pattern according to the invention. The back of the support layer (4) is provided with an adhesive layer (12) as shown in Fig. 2, by means of which the surface sample is adhered to a selected surface of the object to be identified or distinguished as a self-adhesive label. During the possible removal of the support layer (4) from the surface of the object (5), due to the adhesive forces in the adhesive layer (12), the light bending elements (8) are deformed, the relief patterns (9) are distorted.

In Figure 2, for the sake of greater clarity, the outlines of the lattice elements (6) are marked with a double line and the boundaries of the surface elements (7a-7f) with a thick line. In reality, these contours or boundaries are only determined by the differences in the relief patterns (9) of the bending members (8).

The surface pattern has a reference direction indicated by an arrow (13) which lies in the plane of the support layer (4). Each embossment pattern (9) is assigned an orientation direction relative to the reference direction, which a

In Figure 2, an arrow (14) indicates. The reference direction and the orientation direction [arrow (13) and arrow (14)] enclose a lateral angle φ.

In general, therefore, the surface of the surface sample is M

HU 208 279 is divided into a grid element B and the grid elements (6) comprise N surface elements (7). M and N are integers greater than 1. The surface pattern also includes N (3), one of which (the cottage) is shown in Figure 1. Each of Figures (3) consists of M parts. The details are arranged so that each lattice element (6) contains for each of the figures (3) one part formed by the light-bending element (9) in the surface element (7) of the lattice element (6). has a relief pattern. Each detail can be assigned a color value and a luminance value as a parameter.

The defining parameters of the bending element (8) implementing the relief pattern (9) of a given detail are the incident light direction indicated by arrow (10), the viewing direction (angle of view) prescribed for the given figure (3) and shown in Figure 1. (15) is indicated by an arrow and represents the luminance value of the detail.

If the relief pattern of the detail (9) is designed as a simple linear bending grid, it is sufficient to specify the spatial density (frequency), the side angle and the cross-section profile as the determining parameter. The angle of reflection Θ of the incident light is determined by the wavelength of the light and the spatial density of the light-deflecting member (8).

The light-bending elements (8) are preferably formed with an asymmetric cross-sectional profile. In this case, when properly dimensioned, the incident light on the bending element (8) having an asymmetric profile or in a specific spatial direction (shown by arrow (17) in Figure 2) is almost completely reflected, or an intensity ratio other than 1: 1 can be achieved, as described in more detail in R. Petit's "Electromagnetic Theory of Gratings" (pages 63 ff and 159 ff).

The arrow direction (17) of the deflected beam (16) is characterized by the side angle φ and the reflection angle Θ. The side angle φ can be set between 0 ° and 360 °. In the case of the symmetrical cross-sectional profile of the light-bending element (8), the perpendicularly incident light is reflected in two spatially uniform distributions. The symmetrical cross-sectional profile is recognizable by the fact that each of the figures (3) can be read from two opposite viewing directions (viewing angles). By contrast, when properly dimensioned asymmetric profiles are used, each of Figures N (3) can be recognized only from a different viewing direction, indicated by an arrow (15). Surface patterns according to the invention in which the bending elements (8) have both symmetrical and asymmetric cross-sectional profiles can be formed at a relatively higher cost, but may have the advantage of producing particularly striking optical effects.

The spatial frequency may vary within each of the light deflecting elements (8), for example, it may be modulated by a predetermined spatial density amplitude. As a result, the deflected light beams (16) are scattered within the range of spatial density amplitude of the reflection angle Θ. This phenomenon is particularly advantageous when the backing layer (4) is very thin and the object (5) is not completely flat, for example in the case of a crumpled banknote paper material. Despite the unevenness, the surface pattern remains to some extent visible, since some of the deflected light beams (16) are still in the viewing direction indicated by the arrow (15) due to the directional scattering.

The luminance values required for the incident direction of the incident light beams (10) and the specific viewing direction (15) determine the relative values of the surface elements (e.g., 7a-7f) of the lattice element (7). or, in the case of fixed surface elements, the relative dimensions of the reflecting surfaces (18) of the light-deflecting elements (8) carried by the surface elements (7).

The intensity of the light beams (16) deflected by the reflection angle a depends on the illuminating surfaces (18) and the light reflection efficiency of the relief patterns (8), except for the illumination and viewing conditions and the cross-sectional profile shape.

If the proportion of the reflective surface N in the lattice element (6) is determined by the luminance values associated with the associated details of Fig. N (3), the relative luminance values of the predetermined lattice elements (6) .

In the embodiment of Figure 2, the surface elements (7a-7f) of the lattice elements (6) are coincident, however, the relief patterns (9) are determined by the luminance values corresponding to the luminance efficiency assigned to the corresponding figures.

Each of the lattice elements (6) is assigned a specific detail of each of the N (3) figures. The lattice elements (6) therefore carry in each of their surface elements (7) a light bending element (8) which provides a relief pattern (9) corresponding to a given detail and assigned to one of the figures N (3), and (18) its surface has the size corresponding to the luminance value parameter assigned to that part. Thus, the lattice elements (6) carry all the relevant data of the portion of the N (3) assigned to them.

Since each of Fig. N (3) has at least one direction of view indicated by arrows (15), the surface sample viewer can see only one of Fig. N (3) from a given view direction under normal (non-diffuse) illumination. By rotating and tilting the support layer (4) containing the surface pattern, sooner or later the other figures (3) become recognizable.

2 as an example. In the embodiment, the number of figures (3) of the surface pattern according to the invention is N = 6, so that the lattice elements (6) also comprise six surface elements (7a-7f). The light bending element (8) implementing the relief pattern (9) associated with a particular portion of the first figure (3) is arranged in the surface element (7a). Similarly, embossing patterns (8) associated with particular details of the second to sixth figures (3)

The light bending elements are arranged in the surface elements (7b-7f), respectively. The surface elements (7a-7f) have a parallelogram shape, coinciding. The size of the reflecting surfaces which determine the relative luminance values in the surface elements (7a-7f) are different according to the prescribed parameters. In Figure 2, the reflecting surfaces (18) of the light-bending elements (8) are indicated by shaded areas. The free surface portions (19) of the surface elements (7a, 7c and 7d), which are not occupied by the reflecting surfaces (18), are perfectly flat surfaces which reflect the light rays incident from the arrow (10) according to the rules of light reflection. These reflection directions are thus also precisely defined, so care must be taken that neither of the directions of view indicated by the arrow (15) coincides, since such coincidence would interfere with the recognition of the figure (3) associated with that direction of view.

It is possible to provide a matt surface design of the free surface portions 19, whereby the free surface portions 19 distribute the incident light rays evenly in all directions, so that their intensity in all directions is so low that the recognition of the figures 3 is not restricted.

Fig. N (3) according to the invention may be a perspective view of the same object in different views, whereby the different angles of view of the N may correspond to the directions of view assigned to the Figures (3). As the surface pattern is rotated, one perspective view of the illustrated object appears in one direction of view, then disappears by rotating the surface pattern, and when it reaches another view direction in Figure (3), it becomes relatively suddenly recognizable in another view. For example, if the object being depicted is a human portrait, the change of view depending on the angle of view is particularly striking.

In another embodiment, N (3) may be an N-illuminated image of the same object. In this case, the figure N (3) differs only in luminosity values.

Advantageously, Figure N (3) may also be utilized such that each Figure (3) shows a piece of contiguous information, such as a company name, text passages, or figures.

Securities, banknotes, etc. When used, the figures (3) can be advantageously utilized, for example, to display the same subtitle in different languages. The viewing directions assigned to the figures (3) can also be arranged in pairs such that a pair of views belonging to the viewing direction pair produces a stereoscopic image.

The following are exemplary steps for forming a surface pattern according to the invention. In the first step, the selected figure N (3) is enlarged to a size corresponding to the surface pattern and divided into intersecting details. For each detail, the characteristic parameters, the color value and the luminance value are determined. The selected viewing direction is then fixed to each of the figures (3).

The above information determines the relief pattern parameters (9), the relative dimensions of the bending elements (8) and the free surface portions (19) for each surface element (7) of the lattice element.

Using the apparatus described in the above-referenced patent application 00805 / 88-4 CH (Swiss), the masterpiece can be made for the imprint of the surface pattern. The two parameters of the relief patterns (9), the spatial density and the cross-sectional profile, determine the type of matrix required to form the reflective surfaces (18) in the thermoplastic layer. The third parameter captures the orientation direction indicated by the arrow (14) and the side angle φ by which the matrix must be rotated before rendering. The above steps performed by the referred device for producing the masterpiece can be digitally controlled.

For example, a matt surface design of the free surface portions (19) can be produced, for example, by means of a special sticker as part of the relief pattern (9).

The above operation is preferably carried out using a computer program.

It is also possible to create the matte finish in a first step on a cover layer, for example, according to CH (Swiss) Patent Application No. 00805 / 88-4, or in a separate process using an embossing roller.

In the final step, the reflective surfaces (18) are pressed into the surface of the cover layer by means of a suitable die.

From the masterpiece, galvanically negatives are produced from the masterpiece in a manner known per se for the printing stamp (see Swiss Patent Application No. CH-PS 594936) by means of which the variable optical surface pattern of the present invention can be stamped into the backing layer (4).

Claims (13)

PATENT CLAIMS A variable optical surface pattern divided into a number of lattice elements comprising active optical optical luminous elements having a spatial density of at least 10 lines / mm, forming a planar pattern embossing pattern, wherein each lattice element (6) has not more than 0.3 mm in size, the lattice elements (6) include N surface elements (7, 7a, 7b ... 7f), the surface elements (7, 7a, 7b ... 7f) each having a light bending element (8), the light-deflecting member (6) within each lattice element (6) is associated with a different image (3) of the surface elements (7, 7a, 7b ... 7f) bearing the element (6). , and the relief patterns (9) realized by the light bending elements (8) are formed according to the surface part (2) to which they belong. Surface pattern according to claim 1, characterized in that the at least one cross-sectional profile of the light-bending elements (8) is asymmetrical and the light-bending elements have a predetermined angle (φ) of between 0 ° and 360 °. HU 208 279 B Surface pattern according to claim 1 or 2, characterized in that the lattice elements (6) are of regular rectangular shape, wherein the largest diagonal of the rectangle is not larger than 0.3 mm. 4. A surface pattern according to any one of claims 1 to 6, characterized in that the relative size of the reflecting surfaces (18) of the light deflecting elements (8) within the lattice element (6) corresponds to predetermined relative luminance values for each lattice element (6). 5. A surface pattern according to any one of claims 1 to 6, characterized in that the relative degree of bending of the light bending elements (8) within the lattice element corresponds to predetermined relative luminance values for each lattice element (6). Surface pattern according to claim 4 or 5, characterized in that each grid element (6) has the same size surface elements (7, 7a, 7b ... 7f). A surface pattern according to claim 6, characterized in that the free surface portions (19) not included in the surface elements (7, 7a, 7b, 7f) not covered by the light-bending element (8) are of a matt surface. 8. A surface pattern according to any one of claims 1 to 3, characterized in that the figure N (3) is N different views of the same object. 9. A surface pattern as claimed in any one of claims 1 to 4, characterized in that Fig. N (3) is the same view of the same object under different illumination directions. 10. A surface pattern according to any one of claims 1 to 4, characterized in that the figures (3) are raster images and the lattice elements (6) of the surface portions (2) have at least two luminosities! degree. 11. A surface pattern according to any one of claims 1 to 3, characterized in that N is an even number and at least one stereoscopic pair is present between the figures (3). 12. A surface pattern according to any one of the preceding claims, characterized in that the surface pattern is part of a larger planar pattern and the contour (1) of the surface pattern is at least partially surrounded by a surface pattern formed by another technique. 13. A surface pattern according to any one of claims 1 to 4, characterized in that the surface pattern is pressed into a support layer (4), the other side of which is provided with an adhesive surface (11).