Title of Invention

VISUALLY IDENTIFIABLE OPTICAL ELEMENT

Abstract So that a visually identifiable optical element, in particular a security element for valve-bearing documents, for example banknotes, credit cards, passes or cheque documents or other articles to be safeguarded, comprising a carrier with a diffusely reflecting visible surface and a metallisation which is applied in a region-wise manner to the visible surface of the carrie which has a surface that appears metallically shinny at the glancing angle is improved in such a way that an article provided with the element is even more effectively protected trom forgery than is possible with known optical elements, it is proposed that the optical element is so designed that the visible surface of the carrier has two carrier regions with different levels of and in particular diffuse reflectivity for light where in a respective sub-region or a plurality of sub- regions of each of the two carrier regions is or are metallised, and that the reflectivity of the metallisation in viewing directions outside a glancing angle range is less than the reflectivity of the carrier region with the higher level of reflectivity or substantially corresponds to same and is grater than the reflectivity of the carrier region with the lower level of reflectivity or substantially corresponds to same. PRICE: THIRTY RUPEES
Full Text

The invention concerns a visually identifiable optical element, in particular a security element for value-bearing documents, for example banknotes, credit cards, passes or cheque documents, or other items to be safeguarded, including a carrier having an in particular diffusely reflecting visible surface and a metallization applied in a region-wise manner to the visible surface of the carrier, with a surface which appears metallically shining at a glancing angle.
In known optical elements the metallization appears either light or dark, in front of tlie background for the metallization, the background being formed by the carrier. Such an optical element is described for example in WO 93/01057.
WO 94/14621 concerns a security element in the form of the band or strip subdivided into adjacent sub-sections in which diffraction structures are incorporated. These diffraction structures defer from each other. Each diffraction structure focus the incident light in a little bit different pre¬determined direction. This angle of reflection decreases or increases from sub¬section to sub-section. This provides the following effect: When the angle of view is changed it creates the effect of movement of a light point along the length of the security element.
WO/93/01057 describes an optical security device, which is in the form of a discontinuous reflecting surface consisting of a succession of individual reflecting elements. Each individual reflecting element forms a uniform mirror capable of reflecting all the incident light. The reflection phenomenon is clearly

apparent to the naked eye and blinds the known optical analysis or reproduction systems.
WO 94/23395 describes an optical data element including a plurality of diffraction zones wherein each zone contains a multiplicity of diffraction gratings. Thus the emphasis is on a secure optical background for a conventional machine-scannable data devices such as barcodes and decrementable data zones. The zones of the data element are illuminated and the resulting beams are detected to provide a signature for the element consisting of a series of discrete signature signals each generated by the plurality of zones and each including portions of relatively different intensities. The diffraction zones are divided into respective square data segments and each segment of the diffraction zone comprises an nxn-square of diffraction grating pixels. The diffraction grating pixels are uniform within each of the diffraction zones and of uniform square dimension, preferably small enough to be unresolvable by help of the human eyes. Each of this grating pixels, when illuminated, will generate a first order diffraction beam.
The use of a carrier with a metallization as a visually identifiable optical element for security or decorative purposes is based on the physically explainable phenomenon that light which impinges from a given direction onto a smooth metal surface can be perceived by a viewer in the form of reflected light at a given viewing direction. If on the other hand the light is not incident from a single given direction but if the light for example involves diffusely incident daylight or light fix)m a diflRise light source, then, in dependence on the orientation of the metallized region relative to the range of angle of incident of

the light, that gives a viewing angle range, referred to hereinafter as the glancing angle range, from which a viewer perceives the metallization as being highly shiny and metallically bright, as a large part of the light which meets the metallization within the range of the angle of incidence is reflected into that glancing angle range. The reflectivity which is dependent on the viewing angle is thus particularly high in that glancing angle range which is determined by the range of the angle of incidence of the light, in other words, a large part of the radiant energy which passes onto the unit of surface area of the metallization is reflected into that glancing angle range. In contrast, for viewing directions outside the glancing angle range, the metallization does not appear shiny to a viewer, but it gives a metallically grey and matt colour impression. In dependence on the light reflectivity of the carrier, that matt colour impression appears either light or dark, relative to the background.
The term metallization is used hereinafter to denote a layer of any structure, which in particular is very thin, having a metallically shiny

surface.
When using visually identifiable optical elements or security elements, the endeavour is to provide that items of authenticity information in respect of the safeguarded article are rendered visible, even to the unpractised lay person, and at the same time forgery, for example in the form of duplication, having regard to known forgery procedures, in particular optical duplication procedures, is made impossible or is made at least sufficiently difficult. Optical elements of that kind however are also used for decorative purposes.
The object of the present invention therefore is to provide an optical element of the kind described in the opening part of this specification, which is easy to produce in an economical fashion and with which an article to be safeguarded can be protected from forgery even more effectively than is possible with known security elements.
In an optical element as described in the opening part of this specification, in accordance with the invention, that object is attained in that the visible surface of the carrier has two carrier regions having different levels of and in particular diffuse reflectivity for light, wherein a respective sub-region or a plurality of sub-regions of each of the two carrier-regions is or are metallised, and that the refleftivity of the metallisation is lower in the viewing directions outside a glancing angle range than the reflectivity of the carrier region having the higher level of reflectivity or substantially corresponds to same and is greater than the reflectivity of the carrier region having the lower level of reflectivity or substantially corresponds to same.
By virtue of the fact that the carrier is divided into at least one region of higher light reflectivity and a region of lower light reflectivity and the levels of reflectivity of those carrier regions and the metallisation satisfy the conditions described above, the visually perceptible information which can be imparted to a viewer by means of the optical element is more varied and diverse, in dependence on the viewing angle; thus, in a given viewing angle, outside the glancing angle range, a metallised sub-region appears dark in front of the background which is formed by the carrier region having the higher level of reflectivity, while another metallised sub-region appears light in front of the background which is formed by the carrier region having the lower level of

reflectivity, if the reflectivity of the metallisation is lower in the first case and greater in the second case, than the reflectivity of the respective carrier region being viewed.
If the reflectivity of the metallisation in a viewing direction outside the glancing angle range substantially corresponds to the reflectivity of the dark carrier region, that is to say if it is not possible to detect a difference in the reflection capability with the naked eye, the metallised sub-region of that carrier region is not perceptible or is scarcely perceptible in front of the background, when viewing outside the glancing angle range. If on the other hand the security element is viewed in the glancing angle range of the metallisation, which is determined by the range of the angle of incidence of the light, the metallisation appears metallically shinily bright relative to both carrier regions. A corresponding consideration applies if the reflectivity of the metallisation, when viewed in a viewing direction outside the glancing angle range, substantially corresponds to the diffuse reflectivity of the bright carrier region.
In that respect, production of the optical element according to the invention is made more difficult only in a fashion which is not worthy of mention, in comparicon with the production of known elements. Thus for example one half of the carrier can be adapted to appear white, in particular with a visible surface of diffusely reflecting white paper, while the other half of the carrier can be coloured black with a level of reflectivity which accordingly can be disregarded.
The portion of the metallisation which is applied to the black region of the carrier, therefore to the region having the lower level of reflectivity, appears, in front of that dark background, as a matt metallic light-grey colour shade. The portion of the metallisation which is applied to the white carrier region and thefefore to the carrier region having the higher level of reflectivity on the other hand appears, in front of-that light background, as a matt metallic dark-grey shade and stands out fron the light background, by appearing dark. If now the optical element is sc oriented, with respect to the direction of the light impinging thereon, that a viewer has the element or the metallised region in front of his eye; in the above-mentioned glancing angle range^ the portion of th( metallisation which partially covers the white region of the carrier m

longer appears dark but appears brilliantly shiny and gleamingly bright. The portion of the metallisation which is applied to the black region of the carrier also appears metallically shinily bright when it is viewed in a viewing direction within the glancing angle range. In this case also the visually perceptible information changes when the orientation of the element or the viewing direction is altered.
Admittedly, by the use of a carrier with a white and a black region, the optical element according to the invention can be produced in a particularly simple and economical fashion, but it can also be found advantageous to better fulfill in particular aesthetic considerations, if the at least two regions on the visible,surface of the carrier are designed in a different way. There is a wide range of possible variations here, within the limits of the teaching afforded by the invention. For example the region of higher light reflectivity may have a light colour shade and the region of lower reflectivity may have a dark colour shade. It is only necessary to ensure that the above-specified relationships in regard to the levels of reflectivity of the respeccive surrounding regions of the carrier and the metallisation respectively are maintained. In particular if the visible surface of the carrier region of lower reflectivity is to appear as a dark-grey colour shade or as some other blackened colour shade, it is possible for the optical element to be so designed that the reflectivity of the metallisation substantially corresponds to the in particular diffuse reflectivity of the dark-grey background, so that the metallisation does not stand out from the dark-grey background for viewing directions which lie outside the glancing angle range, but only becomes visible to a viewer, when viewed within the glancing angle range.
It will be appreciated that the region-wise metallisation of the respective carrier regions can be of any shape, that is to say it can also be applied to the carrier, in the form of characters or symbols.
In the simplest case, the region-wise metallisation of the carrier regions can be embodied by a single, coherent portion of a metal layer of any geometrical shape, which is applied to the carrier region, covering over the boundary between the light and the dark carrier region. It is however also possible for a plurality of sub-regions and in particular a multiplicity of sub-regions of the two carrier regions to be metallised; tKus, the metallisation can be applied to the carrier, forming a visually

perceptible pattern. In that respect, the pattern can cover over the carrier, in the form of regularly arranged sub-regions of any geometrical shape, in which.case the background always remains visible between the metallised sub-regions. In that respect, it can be found to be particularly advantageous that the metallisation is applied to the carrier in the form of a dot or line grid pattern which produces a visually perceptible half-tone image.
In order further to increase the number of the items of information which can be transmitted by means of the optical element and in order thus more effectively to communicate items of information about a safeguarded article and at the same time to make it more difficult to forge the optical element or the safeguarded article, it is found to be advantageous for the carrier to have a plurality of regions of the same reflectivity. That can be embodied in a very simple manner in that for example a square carrier or carrier portion is divided by a notional vertical line and a horizontal line into four square portions, of which the portions disposed on a respective diagonal are of an identical configuration and form the carrier region having the higher or lower level of reflectivity. It will also be appreciated that any other conceivable ways of dividing the carrier into ■regions of higher and lower levels of light refectivity are embraced by the teaching according to the invention.
Optical elements according to the invention may also include more than two carrier regions or groups of carrier regions of different reflectivity. The relationships in regard to the levels of reflectivity of the individual carrier regions and the associated metallisations are then to be applied accordingly.
In a particularly preferred embodiment of the optical element at least one of the carrier regions is provided with a differing level of reflectivity which in turn varies in dependence on the viewing angle. In other words, upon a change in the .viewing angle, for example by pivoting the carrier about an axis which is disposed in its plane, there is not only a change in the reflectivity of the metallisation, for example by virtue of a transition into the glancing angle range or by departing from the glancing angle range, but there is also a change in the reflectivity of the carrier.region surrounding the metallisation. For that purpose the visible surface of the carrier region can be covered for example with an optically

r
effective thin-film coating which for example imparts a white colour impression for certain viewing directions and for example a colour impression that appears as green, for other viewing directions. It is however also conceivable for the visible surface of the carrier region to be of such a nature, by virtue of a suitable coating thereon, that the coating appears transparent for viewing directions outside the glancing angle range and thus the reflectivity of the visible region of the carrier is determined by the carrier region which is under the coating, while in another viewing angle range, in particular in the glancing angle range, the coating forms a coloured, for example violet background for the metallisation. It is further possible for various portions of the visible surface of the carrier to be coated with different substrates so that the various portions of the carrier, outside the glancing angle range, impart different colour impressions, but possibly also only one colour impression. When the transition into the glancing angle range occurs, the various substrates can then preferably "react" in different ways, that is to say, the different portions of the visible surface of the carrier can impart different changes in image or colour to a viewer, when moving into the glancing angle range.
, „ In a further embodiment of the invention, ii, is proposed that, instead of two carrier regions which are spatially separated from each other, with different levels of reflectivity, there is a carrier region with a level of reflectivity which varies in dependence on the lighting or viewing angle, that carrier region being such that, outside the glancing angle range of the metallisation, there are viewing directions in which the reflectivity of the metallisation is less than the reflectivity of the carrier region or substantially corresponds to same, and that there exist other viewing directions in which the reflectivity of the metallisation is greater than the reflectivity of the carrier region or substantially corresponds to same.
The effect produced at first by the provision of two carrier regions with different levels of reflectivity, namely that a metallisation appears on the one hand light and on the other hand dark, depending on the background in front of which it is viewed, can be produced, in the case of an optical element designed as described above, by varying the viewing angle (positive/negative flip). Thus, it is possible for the carrier to

be such that, in a viewing direction outside the glancing angle range, the metallisation appears dark relative to the background which is formed by the visible surface of the carrier, and that, in another viewing direction, the metallisation appears light in front of the carrier background, and in particular the carrier appears in a different colour from that in which it appears in the first-mentioned viewing direction. In that way, different ideas in regard to image or motif can be aroused on the part of a viewer. It is also possible for the optical element to be such that a change in the reflectivity or the colour of the carrier can be observed when the viewing direction moves into the glancing angle range of the metallisation or when it moves out of the glancing angle range.
Such effects can be achieved over a wide range of variations, for example by widely varying, optically effective thin-film coatings on the visible surface of the carrier, as has already been described in itself hereinbefore. An optical element can therefore be so designed that not only is it possible to provide a transition from a condition with a metallisation which appears dark against the background, into a condition with a metallisation which appears light against the background, but in that respect, at the same time, there is a change in the colour impression originating from the carrier, for example fro;:: '.-.'hite to violet.
It is also possible to envisage carrier region coatings which, in viewing directions outside the glancing angle range of the metallisation, appear transparent, and thus do not or scarcely influence the reflectivity of the carrier and possibly also the metallisation, as well as the light/dark and the dark/light contrast of the metallisation in relation to the carrier, but which, in viewing directions within the glancing angle range, form a coloured, optically perceptible background for the metallisation and possibly also influence the colour impression of the metallisation. This could appear for example as a golden colour.
The optical effectiveness of the carrier coating can be based on per se known physical effects such as extinction or superimposition of light waves, or on the chemical composition of the substances used for this purpose.
In a further preferred embodiment of the optical element, structures producing diffraction and/or interference are integrated into the metallisation. By virtue of the incorporation*of such structures, which

are also to be referred to as diffraction structures, into the metallically shiny surface regions, spectral colour effects can additionally be observed in diffraction angles which are determined by the structure and the 'frequencies of the incident light, in particular also outside the actual glancing angle range. An optical element of such a configuration imparts additional items of information and is therefore even more secure in regard to forgeability thereof.
In a still more comprehensive configuration of the invention, it is proposed that optical elements are so designed that the metallisation includes a relief-like structure comprising metallically shiny raised portions which are elongated in substantially mutually parallel relationship, and that the troughs between the raised portions have a surface structure which imparts a metallically matt image impression. When an optical element of such a configuration is viewed in a direction substantially perpendicularly to the linearly elongated raised portions, the metallisation, within its glancing angle range, is perceptible as metallically shinily bright. In contrast, in a viewing direction substantially parallel to the linearly extended raised portions, the surface structure provided in the troughs between the raised portions acts in the form of an image impression which appears matt. Thus, when viewing the metallisation within the glancing angle range, it is possible, by turning the optical element about an axis which extends approximately perpendicular to the plane of the carrier, to change from an image impression which appears metallically shiny, to an image impression which appears metallically matt, or vice versa. In that way it is also possible to control the light/dark perception relative to a background with a level of reflectivity which is greater than the metallisation outside the glancing angle range thereof and lower than the metallisation within the glancing angle range thereof.
The invention also concerns a value-bearing document carrier, in particular in the form of a portion of a web of flat material, for example of paper or plastic material, which has been improved in regard to its anti-forgery security, by virtue of the fact that it has a security element according to the invention. In preferred value-bearing document carriers, the carrier of the security element is formed by the value-bearing document carrier itself.

Accordingly the present invention provides a Visually identitlable optical element, in particular a security element for security documents, e.g. banknotes, credit cards, identity cards or cheque documents, or other articles to be safeguarded, comprising a substrate having a visible face that in particular diffusely reflective and a metallization that is applied to parts of the visible face of the substrate and has a surface that appears to be metallically glossy at a gloss angle, characterized in that the visible face of the substrate has two substrate areas with different levels of reflectivity, in particular diffuse reflectivity, for light, in each case one subarea or more than one subarea of each of the two substrate areas being metallized, and in that reflectivity of the metallization, in viewing directions outside the gloss angle range, is lower than the reflectivity of the substrate area having the higher reflectivity or essentially corresponds to this reflectivity and is higher than the reflectivity of the substrate area having the lower reflectivity or essentially corresponds to this reflectivity.

Further features, advantages and details of the invention are apparent from the accompanying drawing and from the following description of advantageous embodiments of the optical element according to the invention. In the drawing: Figure 1 is a diagrammatic view showing the principle of a known optical
element, Figure 2 is a diagrammatic view of an optical element according to the
invention. Figure 3 is a diagrammatic view of a further embodiment of the optical
element according to the invention, Figure 4 is a diagrammatic view of a third embodiment of the optical
element according to the invention with a metallisation in
pattern form. Figure 5 is a diagrammatic view of a fourth embodiment of the optical
element according to the invention with a metallisation in the
form of dot and line grid patterns. Figure 6 is a diagrammatic view of a fifth embodiment of the optical
element according to the invention with a plurality of carrier
regions having the same reflectivity. Figure 7 is a diagrammatic view of a sixth embodiment of the optical
element according to the invention with a carrier region of
varying reflectivity and with a metallisation which has
structures, and Figure 8 is a diagrammatic view of a value-bearing document carrier with
an optical security element according to the invention. Figure 1 shows an optical element which is fundamentally known, being generally identified by reference numeral 1 and being used as a security element. The optical element 1 includes a flat extensive carrier 2 having a sub-region 4 to which a metallisation 6 (not shown in detail) is applied. The metallisation 6 can be formed from a homogenous metal layer or it can be formed by metallic grid pattern dots which generate a half-tone image. The carrier 2 has for example an optically bright, diffusely reflecting visible surface 8 which is towards a viewer V and which forms the background for the metallisation 6, but which in turn can also include items of information, for example in the form of water marks, thin hatching lines-, etc.. If light impinges on the element i or the metallisation 6

within a range of angle of incidence 6 from an in particular diffuse light source or in the form of diffuse daylight which enters through a window, then a large part of the incident light can be perceived in the form of reflected light within a glancing angle range a. The metallisation then appears to be highly shiny and stands out as metallically shiny and of bright appearance, from the visible surface 8 of the carrier 2; the visible surface 8 is admittedly optically bright but it provides diffuse reflection. In contrast, in viewing directions outside the glancing angle range a the metallisation 6 imparts a matt, metallic dark-grey colour shade which stands out as dark in front of the optically bright background of the carrier 2.
Figure 2 shows a first embodiment of the optical element according to the invention. It includes a carrier 10 whose visible surface 12 is divided into a region 14 with a high level of diffuse light reflectivity 0;> and a region 16 with a low level of diffuse light reflectivity o. The region 14 conveys a white colour impression and therefore reflects the frequencies of the visible spectrum equally, while the region 16 absorbs the visible light and therefore appears black. The regions 14, 16 may also in turn include items of information. Reference numeral 18 indicates a .sub-region of the carrier 10 to which a metallisation 20 is applied in a manner not shown in greater detail herein. In that respect, half of the metallisation 20 or the sub-region 18 is disposed in the light region 14 while the other half is in the dark region 16. The metallisation 20 has a reflectivity o„, which, in a viewing direction outside its glancing angle range a described in connection with Figure 1, is less than the reflectivity o^, of the region 14 with the higher level of reflectivity, but it is higher than the reflectivity o-,^ of the region 16 with the low level of reflectivity. When the sub-region 18 is viewed from a direction which, having regard to the incident light, lies outside the glancing angle range a, the metallisation 20 appears dark in front of the light background of the region 14, while the portion of the metallisation 20, which is applied to the dark carrier region 16, appears light. Accordingly, items of optical information which are different from each other can be conveyed to a viewer by means of one and the same metallisation. In viewing directions within the glancing angle range o the metallisation appears light relative to both carrier regions 14, 16 as the reflectivity of a smooth metallic

surface within its glancing angle range is greater than the reflectivity )f the diffusely reflecting carrier.
Figure 3 shows another embodiment of the optical element according to the invention, which differs from the embodiment shown in Figure 2 in that, instead of a coherent metallisation 20 which covers in a region-wise manner the two carrier regions of different levels of reflectivity, there are two metallised sub-regions 24, 26 on a carrier 28. The sub-region 24 is within a light carrier region 30 and the sub-region 26 is within a dark carrier region 32. With that optical element, by means of the same metallisation, it is possible to communicate two different items of visually perceptible information which come from spatially separated regions of the carrier. The sub-regions 24, 26 may also be in the shape of different symbols.
Figure 4 shows a particularly preferred embodiment of the optical element according to the invention. In the illustrated case, the metallisation is applied to the carrier in the form of a regular pattern which covers over the visible surface 34 of a carrier 36. The pattern is formed by metallised square sub-regions 38 which touch each other at the corners in the manner of a chessboard pattern. In viewing directions outside the glancing angle range, in front of the light background of a carrier region 40 with a high level of reflectivity, the metallised sub-regions 38 appear dark. In the illustrated case, a carrier region 42 with a low level of light reflectivity has a visible surface of such a grey shade that, in a viewing direction outside the glancing angle range a the metallised sub-regions 38 which cover over that carrier region 42 do not stand out from the grey background and therefore cannot be perceived by a viewer (this is not shown here however). In this case, the reflectivity of the metallisation o„ substantially corresponds to the reflectivity o,, of the carrier region 42. The carrier region 42 therefore appears grey over its entire extent. The pattern shown in Figure 4 can only be perceived on the carrier region 42 when the carrier region 42 is viewed in a direction within the glancing angle range. Such a security element can be reliably handled and understood, even by an unskilled lay person.
As is clear from Figure 5, the metallisation can also be formed by different forms of dot or line grid patterns which produce a half-tone image 52. In the. illustrated case,, the pattern dots 50 are applied to a carrier region 54 with a high level of light reflectivity. Applied to a

carrier region 56 with a low level of light reflectivity is a metallisation in a form of a line pattern of strips 58 which extend substantially parallel to each other. A visually perceptible half-tone image is produced by varying the width of the lines or strips 58 over their longitudinal extent.
Figure 6 shows a further preferred embodiment of the optical element according to the invention, in which a carrier 60 is divided into a plurality of regions 62 and 64 respectively of equal reflectivity. The regions indicated by reference numeral 62 have a lower level of reflectivity and therefore appear dark while the regions 64 have a high level of reflectivity and consequently appear light. In the regions 62 and 64 arranged at the top in Figure 6, there is a metallisation 66 and 68 respectively, in the form of metallic pattern dots which combine to form digits. In the carrier regions 62 and 64 which are arranged at the bottom in Figure 6, a metallisation is applied to the carrier 60, in each case in the form of a letter. When the element is viewed outside the glancing angle range the letter "D" appears light in front of the dark background of the carrier region 62 while the letter "M" appears dark in front of the light background of the carrier region 64.
The optical elements shown in Figures 2 to 6 or the visible surfaces of the carrier regions 14, 16, 30, 32, 40, 42 can be of such a nature and configuration, for exam'ple by means of an optically effective thin-film coating, that their reflectivity alters in dependence on the lighting or viewing angle. It is possible for example that the carrier region 64 of the carrier 60 shown in Figure 6 appears white in a given viewing direction, whereas in another viewing direction, it forms a coloured background for the patterned metallisation 68.
If, before the metallisation in pattern form is applied to the sub-region of the carrier region 64, which is to be metallised and which is in the form of the number "10", that sub-region is optically darkened, in particular blackened, it is possible for the patterning to be such that, in the glancing angle range, the reflectivity of the patterned metallisation "68 substantially corresponds to the reflectivity of the carrier region 64 so that, in the glancing angle range, the symbol represented by the patterned metallisation is not perceptible or is scarcely perceptible.

It is further possible for structures which have an optical-diffraction effect, that is to say which cause diffraction and/or interference, to be integrated into the metallised sub-regions of the optical elements shown in Figure 2 to 6. In the diffraction angles, in particular outside the actual glancing angle range, it is then possible to observe defined spectral colour effects which, as additional authenticity information, make it more difficult to forge the article to be safeguarded.
Figure 7 shows a further advantageous embodiment of the optical element according to the invention, in which a carrier region 74 which forms the entire visible surface 70 of a carrier 72 is of such a configuration, by virtue of a suitable, optically effective thin-film coating, in particular a special-effect pigment, that it exhibits varying reflectivity in dependence on the lighting or viewing angle; thus, when viewed in a first viewing direction the carrier region 74 conveys a first colour impression and, when viewed in a second viewing direction, it conveys a colour impression of a different colour.
A sub-region 76 of the carrier region 74 carries a metallisation 78 which appears dark relative to the carrier region 74, in a viewing angle range outside its glancing angle range a, while in another viewing direction, in particular within its glancing angle range, lt appears light. The surface of the metallisation 78 includes relief-like metallically shiny raised portions 80 which are extended substantially parallel to each other, while troughs 82 between the raised portions 80 have a surface structure 84 which conveys a metallically matt image impression. When the optical element is viewed in a direction as indicated by an arrow 85 within the glancing angle range a and substantially perpendicularly to the linearly extended raised portions, the metallisation 78 appears metallically shinily
portions 80, the surface structure provided in the troughs 82 becomes visible arid Lhus becomes optically effective so that a matt, metallically grey image impression is conveyed to a viewer.
Figure 8 shows a value-bearing document carrier 90 with a security element 92. The value-bearing document carrier 90 includes a web of flat plastic material, as is used in particular for the production of cheque cards or the like, and on its-visible surface 94 it has a region 96 which appears light and a region 98 which appears dark, which regions are covered

by a metallisation in the form of metallised sub-regions 100 arranged in a chessboard-like fashion. The mode of operation of this value-bearing document carrier 90 which is designed in accordance with the invention corresponds to the mode of operation of the optical elements described with reference to the foregoing Figures.


WE CLAIM:
1. A Visually identifiable optical element, in particular a security element for security documents, e.g. banknotes, credit cards, identity cards or cheque documents, or other articles to be safeguarded, comprising a substrate having a visible face that in particular diffusely reflective and a metallization that is applied to parts of the visible face of the substrate and has a surface that appears to be metallically glossy at a gloss angle, characterized in that the visible face (12, 34) of the substrate (10, 28, 36) has two substrate areas (14, 16; 30, 32; 40, 42) with different levels of reflectivity, in particular diffuse reflectivity, for light in each case one subarea (18. 24, 26) or more than one subarea (38) of each of the two substrate areas (14, 16; 30, 32; 40, 42) being metallized, and in that reflectivity (CTM) of the metallization, in viewing directions outside the gloss angle range (a), is lower than the reflectivity of the substrate area (14, 30, 40, 54, 64) having the higher reflectivity () or essentially corresponds to this reflectivity and is higher than the reflectivity of the substrate area (16, 32, 42, 56) having the lower reflectivity (aT 2. The optical element according to Claim 1, wherein the metallization is applied to the substrate in the form of a point grid or line grid (50) that produces a visually perceptible half-tone image (52)
3. The optical element according to claim 1 or 2, wherein the metallization is applied to the substrate so as to form a visually perceptible pattern, a character, a symbol or a figure.

4. The optical element according to Claim 3, wherein the metallization covers the substrate (36) in the form of regularly arranged rhomboidal subareas (38)
5. The optical element according to one or more of the preceding claims, wherein the substrate (60) has a plurality of regions (62, 64) of equal reflectively.
6. The optical element according to one or more of the preceding claims, wherein the substrate has more than two areas with different levels of reflectivity.
1. The optical element according to one or more of the preceding claims, wherein metals with different levels of reflectivity are used for the metallization of parts of the substrate areas.
The optical element according to one or more of the preceding claims, wherein at least one of the substrate areas (14, 16; 30, 32; 40, 42) is designed with a reflectivity that varies as a function of the viewing angle.
The optical element according to claim 1, wherein the two carrier regions are formed by a carrier region having a reflectivity which dependence on the lighting or viewing angle and the carrier region (74) is such that there are viewing directions outside the glancing angle range (a), in which the reflectivity (OM) of the metallization (78) is less than the reflectivity (aT)of the carrier region (74) or substantially corresponds to same and there exist other viewing directions in which the reflectivity (OM) of the metallization is greater than the reflectivity (OT) of the carrier region (74)

' or substantially corresponds to same.
10. The optical element according to one or more of the preceding claims,
wherein the substrate area (74) has an optically active thin-film coating.
11. The optical element according to one or more of the preceding claims,
wherein the metallization (78) has structures effecting diffraction and/or
interference integrated into it.
12. The optical element according to one or more of the preceding claims,
wherein the metallization (78) comprises elevations (80) that are like a
relief, metallically glossy and extended essentially parallel to one another,
and the valleys (82) between the elevations have a surface structure (84)
that conveys an impression of a metallically matt image.
13. Security document substrate, in particular in the form of a flat material
web of paper or plastic, characterized by an optical security element (92)
according to one or more of Claims 1 to 11.
14. A Visually identifiable optical element substantially as herein described
with reference to figures 2 to 8 of the accompanying drawings.



Documents:

1167-mas-1995 others.pdf

1167-mas-1995 abstract.jpg

1167-mas-1995 abstract.pdf

1167-mas-1995 claims.pdf

1167-mas-1995 correspondence others.pdf

1167-mas-1995 correspondence po.pdf

1167-mas-1995 description (complete).pdf

1167-mas-1995 drawings.pdf

1167-mas-1995 form-1.pdf

1167-mas-1995 form-26.pdf

1167-mas-1995 form-4.pdf

1167-mas-1995 form-9.pdf

1167-mas-1995 petition.pdf


Patent Number 192648
Indian Patent Application Number 1167/MAS/1995
PG Journal Number 30/2009
Publication Date 24-Jul-2009
Grant Date 23-Dec-2004
Date of Filing 07-Sep-1995
Name of Patentee M/S. LEONHARD KURZ GMBH & CO
Applicant Address SCHWABACHER STRASSE 482 90763 FURTH
Inventors:
# Inventor's Name Inventor's Address
1 REINHART WERNER OBERE KANALSTRASSE 8A 90429 NURNBERG
PCT International Classification Number B41M3/14
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA