AU2011101065A4 - Composite window security device - Google Patents

Abstract

A security document or device includes an area formed from a transparent plastics material (10), at least one partially opacifying layer (12, 14,16) applied to 5 a first side of the transparent plastics material, at least one partially opacifying layer (22,24) applied to the opposite second side of the transparent plastics material, at least one coloured layer (18, 26) on one or both of said first and second sides of the transparent plastics material (10), and at least one security layer (28) applied on one or both sides of the transparent plastics material. The 10 partially opacifying layers (12, 14, 16, 22, 24) on both sides of the substrate are omitted in at least one area to form a window area (11) in the security document or device. The security layer (28) extends at least partially over the window and into the surrounding region covered by the partially opacifying layers (12, 14, 16, 22, 24). The partially opacifying layers (12, 14, 16, 22, 24), the at least one 15 coloured layer (18, 26), the window area (11) and the at least one security layer (28) cooperate to produce a first image visible in reflection from the first side of the transparent plastics, a second image visible in reflection from the second side of the transparent plastics material, and a third image visible in transmission from both sides of the transparent plastics material. NJ -P hi m h-.) .. ........c; :1. 11...

Description

1 COMPOSITE WINDOW SECURITY DEVICE FIELD OF THE INVENTION The invention relates to security documents or devices, such as bank notes, cheques, certificates and the like, and to the methods of forming these 5 security documents or devices. In particular the invention relates to security documents or devices with a composite window that produces different images in reflection and transmission and that is difficult to reproduce or counterfeit. BACKGROUND TO THE INVENTION The use of a transparent area known as 'window' in the substrate of a 10 security document or device has previously been proposed as an improvement to the security of banknotes, cheques, certificates and the like. For example, WO 83/00659 discloses a security token such as a banknote or identity card that has a sheet-like substrate that is made of a transparent polymer layer coated with layers of opaque adhesive material. The opaque material only partially covers 15 the transparent layer in a way as to form a transparent 'window' that allows the inspection of a security device such as a diffraction grating. Further improvements to security documents and devices have proposed the use of a 'half window'. For example, WO 98/13211 discloses a banknote which has a transparent polymer layer with opacifying layers. The opacifying 20 layers partially cover the transparent layer and the security device in a way that forms a 'half window', where only part of the security device can be viewed through the transparent layer. This allows a first image to be viewed from one side of the security device and a second and different image to be viewed from the opposite side of the security device. 25 It is desirable to produce a security document or device that can produce attractive visual effects from different viewing positions that is difficult to reproduce or counterfeit. SUMMARY OF THE INVENTION According to one aspect of the invention, there is provided a security 30 document or device including at least one area formed from a transparent plastics material, at least one partially opacifying layer applied to a first side of the transparent plastics material, at least one partially opacifying layer applied to the opposite second side of the transparent plastics material, at least one coloured 2 layer on one or both sides of said first and second sides of the transparent plastics material, and at least one security layer applied on one or both sides of the transparent plastics material, wherein the partially opacifying layers on both sides of the transparent plastics 5 material are omitted in at least one area to form a window area in the security document, the security layer extends at least partially over the window area and into the surrounding region of the transparent plastics material covered by at least one of the partially opacifying layers, and 10 the partially opacifying layers, the at least one coloured layer, the window area and the at least one security layer cooperate to produce a first image visible in reflection from the first side of the transparent plastics material, a second image visible in reflection from the second side of the transparent plastics material, and a third image visible in transmission from both sides of the 15 transparent plastics material. The first image viewable in reflection from the first side of the transparent plastics material and the second image viewable in reflection from the second opposite side of the transparent plastics material are preferably different images. The third image that can be seen in transmission produced by the 20 combination of the partially opacifying layers, the coloured printed layer or layers and the at least one security layer is preferably a different image from the first and second images. However, parts of the first and second images may be present in the third image to provide an attractive visual effect. Therefore, the present invention advantageously provides a security 25 document or device that has a complex composite window device that can be easily identified by the different images seen in reflection and transmission from one or both sides of the document or device. Preferably the at least one security layer is selected from an optically variable layer, a reflective metallic layer, a layer containing a magnetic image, 30 and an optically variable layer containing a magnetic image. At least one of the partially opacifying layers on one or both sides of the transparent plastics material preferably comprise a layer of opacifying ink. Such an opacifying ink layer may comprise a pigmented coating. The pigmented 3 coating may comprise a pigment, such as titanium dioxide, dispersed within a binder or carrier. The binder or carrier may be a polymeric material. Alternatively, at least one of the partially opacifying layers may be formed from paper or other fibrous material, such as a fibrous cellulosic material. 5 Each of the partially opacifying layers is preferably applied in a thickness sufficient to allow the partial transmission of light. When viewed in reflection, however, the partially opacifying layers obscure the transparent plastics material and any other layers underneath. In a preferred embodiment, the security document or device includes a 10 plurality of opacifying layers applied to at least one side of the transparent plastics material. At least one of said plurality of partially opacifying layers preferably covers more or less of the transparent plastics material than another of said plurality of partially opacifying layers. In this manner, said plurality of at least partially opacifying layers can produce different areas of different or varying 15 partial opacity when viewed in transmission. This effect is sometimes referred to as a shadow image in security documents which have opacifying ink layers. A similar effect of different or varying partial opacity, known as a watermark, can be produced by varying the thickness of a partially opacifying paper or fibrous layer. The security document or device may have a plurality of partially 20 opacifying layers applied on both sides of the transparent plastics material. At least one of said plurality of partially opacifying layers preferably covers more or less of the transparent plastics material than another of said plurality of partially opacifying layers on the same side. The opacifying layer or layers on one side may cover a different area of the transparent plastics material than the opacifying 25 layer or layers on the opposite side. The at least one coloured layer on one or both sides of the transparent plastics material preferably comprises a coloured printed layer. Alternatively, the at least one coloured layer may comprise a layer of coloured foil or other material. The at least one coloured layer is preferably arranged to allow some transmission 30 of light through the security document or device. This may be achieved by applying the coloured layer in a thickness which allows some transmission of light, and/or by using a coloured translucent layer. The at least one coloured layer preferably covers more or less of the area covered by at least one of the 4 opacifying layers on the same side of the transparent plastics material. The at least one coloured layer and said at least one opacifying layer in combination may define a shadow image viewable in reflection from one or both sides of the security document or device. 5 In a preferred embodiment, one or more coloured layers are provided on both sides of the transparent plastics material. The coloured layers on opposite sides, in combination with the opacifying layers, preferably define different images. The at least one security layer may include at least one reflective metallic 10 layer that is composed of a metallic ink or foil, such as a hot stamp foil. The reflective metallic layer provides a level of security against any form of digital reproduction and thus is difficult to reproduce. The security document or device may have at least one security layer that includes at least one diffractive image. 15 Preferably the security document or device has at least one security layer that provides at least one colour shift between a first colour or hue, and a second colour or hue depending on the viewing angle. Such a security layer may be formed from an optically variable ink such as an OVI T M produced by SICPA HOLDING SA. 20 The security layer may include a material which has magnetic properties. For example, the security layer may include magnetic particles which reveal a magnetic image which is normally hidden, but which appears when the security document or device is exposed to a magnetic field. This makes the security document or device more difficult to counterfeit and provides added security. 25 In a particularly preferred embodiment, the security layer comprises an optically variable layer that includes a material which has magnetic properties. Examples of suitable optically variable security layers with magnetic properties are a SPARK OVITM patch produced by SICPA, the magnetic optically variable pigment described in W002/073250 A2, and the transfer foil containing optically 30 variable magnetic pigment described in W02011/012520 A2. According to another aspect of the invention, there is provided a method of producing a security document or device which includes the steps of providing a transparent plastic material, 5 applying at least one partially opacifying layer to a first side of the transparent plastics material, applying at least one partially opacifying layer to the opposite second side of the transparent plastics material, 5 applying at least one coloured printed layer on at least one of the first and second sides of the transparent plastics material, and applying at least one security layer on one or both sides of the transparent plastics material, wherein the partially opacifying layers on both sides of the substrate are omitted in 10 at least one area to form a window in the security document, the security layer extends at least partially over the window and into the surrounding region of the transparent plastics material covered by at least one of the partially opacifying layers, and the partially opacifying layers, at least one of the coloured printing layers, 15 the window area and the at least one security layer cooperate to produce a first image visible in reflection from the first side of the transparent plastics, a second image visible in reflection from the second side of the transparent plastics material, and a third image visible in transmission from both sides of the transparent plastics material. 20 The method may also include the step of forming the least one security layer from a selection of an optically variable layer, a reflective metallic layer, a layer containing a magnetic image, and an optically variable layer containing a magnetic image. The at least one security layer is preferably provided on the outer surface 25 of the opacifying layer or layers and the at least one coloured layer on at least one side of the transparent plastics material. From this side, the whole area of the security layer is visible in reflection to provide one of the first and second images. When viewed in reflection from the opposite side, only part of the area of the security layer is visible through the window with the remaining part of the security 30 layer obscured by the opacifying layers and the at least one coloured layer to provide the second, different image. When viewed in transmission from the opposite side, a third, different image is produced. This is because the partially opacifying layers and the at least one coloured layer are not completely opaque 6 and allow some transmission of light. The result is that the part of the security layer which overlaps the window area is completely visible, and the part of the security layer which overlaps the opacifying layer or layers can be seen, though not as strongly, in transmission from the opposite side. 5 The method may also include the step of applying a plurality of partially opacifying layers on one or both sides of the transparent plastics material. At least one of said plurality of partially opacifying layers preferably covers more or less of the transparent plastics material than another of said plurality of partially opacifying layers on the same side. The opacifying layer or layers on one side 10 may cover a different area of the transparent plastics material than the opacifying layer or layers on the opposite side. The partially opacifying layers may be applied in a printing process, preferably a Gravure printing process, although other forms of printing, such as offset printing or screen printing may be used. 15 Alternatively, the partially opacifying layers may be formed from paper or other fibrous material, such as a fibrous cellulosic material applied to the transparent plastics material. The at least one coloured layer on one or both sides of the transparent plastics material is preferably applied in a printing process, such as by offset 20 printing, screen printing or intaglio printing. The at least one coloured layer may be formed from a permanently coloured ink or a coloured translucent ink. Alternatively, the at least one coloured layer may comprise a layer of coloured foil or other material which is applied by bonding or laminating the foil or other material to the security document or device. 25 The at least one coloured layer preferably covers more or less of at least one of the opacifying layers on the same side of the transparent plastics material. The at least one coloured layer and said at least one opacifying layer in combination may define an image viewable in reflection from said same side of the transparent plastics material. 30 In a preferred embodiment, one or more coloured layers are provided on both sides of the transparent plastics material. The coloured layers, in combination with the opacifying layers on both sides, preferably define different images.

7 Preferably the method also includes forming the security document or device wherein each of the first image visible in reflection from the first side of the transparent plastics, the second image visible in reflection from the second side of the transparent plastics material, and the third image visible in transmission 5 from both sides of the transparent plastics material are all different. The at least one security layer may be applied in a printing process or as a foil. The security layer may be a reflective metallic layer composed of a metallic ink or foil. 10 A preferred method may include the step of forming the at least one security layer to contain at least one diffractive image. An alternative preferred method may include the step of forming the at least one security layer to provide at least one colour shift between a first colour or hue and a second colour or hue depending on the viewing angle. Such a 15 security layer may be formed from an optically variable ink such as an OVITM produced by SICPA HOLDING SA. In a particularly preferred embodiment, the security layer comprises an optically variable layer that includes a material which has magnetic properties. Examples of suitable optically variable security layers with magnetic properties 20 are a SPARK OVITM patch produced by SICPA, the magnetic optically variable pigment described in W002/073250 A2, and the transfer foil containing optically variable magnetic pigment described in W02011/012520 A2. BRIEF DESCRIPTION OF THE DRAWINGS In order that the present invention may be more readily understood, a 25 preferred embodiment thereof will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a sectional view through a security document or device including a composite window in accordance with a preferred embodiment of the present invention. 30 Figures 2a-1 1 b show step by step formation of the security document or device of Figure 1 in accordance with a preferred method of the present invention; more particularly: 8 Figure 2a shows a sectional view of a first partially opacifying layer applied to a first side of a transparent plastics material; Figure 2b shows the image formed from the layer of Figure 2a in reflection from the first side; 5 Figure 3a shows a sectional view similar to Figure 2a including a second partially opacifying layer applied to the first side; Figure 3b shows the image formed from the layers of Figure 3a in reflection from the first side; Figure 4a shows a sectional view similar to Figure 3a including a third 10 partially opacifying layer applied to the first side; Figure 4b shows the image formed from the layers of Figure 4a in reflection from the first side; Figure 5a shows a sectional view similar to Figure 4a including a coloured printed layer applied to the first side; 15 Figure 5b shows the image formed from the layers of Figure 5a in reflection from the first side; Figure 6a shows a sectional view similar to Figure 5a including a partially opacifying layer applied to the second, opposite side of the transparent plastics material; 20 Figure 6b shows the image formed from the partially opacifying layer of Figure 6a in reflection from the second side; Figure 7a shows a sectional view similar to Figure 6a including a second partially opacifying layer applied to the second side; Figure 7b shows the image formed from the layers of Figure 7a in 25 reflection from the second side; Figure 8a shows a sectional view similar to Figure 7a including a coloured layer applied to the second side; Figure 8b shows the image formed from the layers of Figure 8a in reflection from the second side; 30 Figure 9a shows a sectional view similar to Figure 8a including a security layer applied to the second side to form the complete composite window; Figure 9b shows the final image formed from Figure 9a in reflection from the second side; 9 Figure 10a shows a sectional view of the complete composite window identical to Figure 9a; and Figure 10b shows the final image formed from the complete composite window of Figure 10a in reflection from the first side. 5 Figure 11a shows a sectional view of the complete composite window identical to Figures 9a and 10a; and Figure 11b shows the final image formed from the complete composite window of Figure 11 b viewed in transmission. 10 DETAILED DESCRIPTION OF THE DRAWINGS Referring now to Figure 1, there is shown a composite window security device including a layer of transparent plastics material 10. The transparent plastics layer preferably comprises a polymeric substrate, such as a biaxially oriented polypropylene of the type used in the production of polymer banknotes. 15 However, other transparent plastics material may be used to form the layer 10. The security device described may be a stand alone security device which can subsequently be applied to a security document, eg by affixing the device within a banknote or other paper or value, or the security device may form an integral part of the security document. In the latter case, the transparent plastics layer 20 may form the base substrate of the banknote or other security documents The security device has a first layer of partially opacifying material 12, applied to a first side of the transparent plastics material 10, a second layer of partially opacifying material 14, applied onto the first layer of partially opacifying material 12, and a third layer of partially opacifying material 16, applied onto the 25 second layer of partially opacifying material 12. Similarly, there is included a first layer of partially opacifying material 22, on the second opposite side of the transparent plastics material 10, with a second layer of partially opacifying material 24, applied onto the first layer of partially opacifying material 22. 30 On the first side of the transparent plastics material 10, a coloured layer 18, is formed on the partially opacifying layers 12, 14 and 16 and similarly on the second opposite side of the transparent plastics material 10, a second coloured layer 26 is formed on the partially opacifying layers 22 and 24.

10 A security layer 28 is provided on the second side of the transparent plastics material 10, on top of the partially opacifying layers 22, 24 and the coloured layer 26. The security layer 28 may be made from any of a selection of an optically variable layer, reflective metallic layer, a layer containing a magnetic 5 image and an optically variable layer containing a magnetic image. In a preferred embodiment, the composite window of Figure 1 contains a security layer 28 formed from an optically variable ink such as OVI T M by SICPA HOLDING SA providing colour shift properties or a reflective metal patch that may also contain diffractive images. The security layer 28 may also be preferably 10 formed from a SPARK OVI T M patch by SICPA HOLDING SA that contains a magnetic image offering a high level of security against reproduction and forgery. In an alternative embodiment, the security layer 28 may be formed from a reflective layer, such as a metallic ink layer or a metallic foil. The reflective layer may include an optically variable device, such as a diffraction grating. 15 As shown, the partially opacifying layers 12, 14, 16, 22 and 24, and the coloured layers 18 and 26 are not applied over the entire surfaces of the transparent plastics material 10, thus leaving an area uncovered to form a 'window' area 11. The security layer 28 at least partly overlaps the 'window' area and partly covers the partially opacifying layers 22 and 24 and coloured printed 20 layer 26. The whole area of the security layer 28 is therefore completely visible when viewed in reflection from the second side of the security document or device corresponding to the second side of the transparent plastics material, but only part of the security layer is visible through the 'window area' when viewed in reflection from the second side of the security document or device corresponding 25 to the second side of the transparent plastics material. Also, as shown in Figure 1, part 29 of the 'window area' 11 is not covered by any layer on the first and second sides of the transparent plastics substrate. It will, however be appreciated that the whole of the 'window' area could be covered by the security layer 28 so that the 'window' area effectively is a 'half-window' area. 30 Each succeeding partially opacifying layer 14, 16, 22 and 24, the coloured layers 18 and 26 and the security layer 28 preferably partly cover different overlapping areas of the transparent plastics material to form a 'composite window' which produces unusual optical effects. For example, partially opacifying 11 layer 14 may cover a different area of the security document or device to the area covered by partially opacifying layer 12, and the coloured layers 18, 26 may cover different areas to the opacifying layers. The composition of the different layers of the composite window may then combine to produce an aesthetically pleasing 5 and complex set of images when viewed in reflection from opposite sides and with variations in opacity to create a different image which is visible in transmission. From the first side of the security document or device, a first image may be seen from the reflection of the set of opacifying layers 12, 14 and 16, coloured 10 printed layer 18 and the transparent plastics material 10 and part of the security layer 28 visible through the window or half-window. From the opposite side of the security document or device, a second image may be seen from the reflection of the set of opacifying layers 22 and 24, coloured printed layer 26, the transparent plastics material 10 and the whole of the security layer 28. The first and second 15 images may also be enhanced by the security layer 28 providing an optically variable image effect, eg having colour shifting properties or diffractive images, and/or by the security layer including a magnetic image. A third image may be seen by viewing the combination of all layers in transmission from either side of the transparent plastics material 10, forming a total composite image that has 20 variations in opacity that creates a shadow image from the partially opacifying layers 12, 14, 16, 22 and 24, transparent area, security layer 28 and complementary graphics produced by coloured layers 18 and 26. Preferably all three images are different, thus increasing the difficulty of reproduction and forgery. 25 Figure 2a is a sectional view showing a first partially opacifying layer 12 applied to a substrate of transparent plastics material 10. The partially opacifying layer 12 does not cover the entire area of the transparent plastics material 10, forming a 'window' area 13. Figure 2b correspondingly shows the image that may be viewed from the reflection of the construction of Figure 2a. The white area of 30 Figure 2b shows the area covered by the partially opacifying layer 12 which in this embodiment has been applied to provide the outline of a frog on a gum tree branch. The 'window' area 13 is consequently in the shape of the frog on the gum tree branch.

12 Figure 3a corresponds to Figure 2a with a second partially opacifying layer14 applied over the partially opacifying layer 12. The layer 14 does not cover the entire area of the transparent plastics material 10. The partially opacifying layer 14 overlaps and covers a partly different area of the transparent 5 plastics material than partially opacifying layer 12 to form a different 'window' area 15 from the window area 13. Figure 3b correspondingly shows the image that may be viewed from the reflection of the construction of the transparent plastics material 10 and the partially opacifying layers 12 and 14 of Figure 3a. It can be seen that the partially opacifying layer 14 covers a different area of the 10 transparent plastics material to partially opacifying layer 12 to form an outline of the frog and a single gum leaf. The 'window' area 15 is fully transparent and in the shape of the frog and the single gum leaf. The parts of the window area 13 that are covered by the overlapping partially transparent opacifying layer form a shadow image from the variation in the opacity between the different areas of the 15 transparent plastics material layer 10 covered by the partially opacifying layers 12 and 14. As shown in Figure 3b, the white region has been formed from the combination of both partially opacifying layers 12 and 14, the grey region (gum leaf branch) is formed from part of the opacifying layer 14 which overlaps the window area 13, and the dark region (frog shape and single leaf) is formed from 20 the full window area 15 of the uncovered transparent plastics material 10. Figure 4a corresponds to Figure 3a with a third partially opacifying layer 16 covering a different area than either of the partially opacifying layers 12 or 14. Figure 4b shows clearly the 'window' area formed of the shape of a frog and single gum leaf, and the feature of the gum leaf branch shape is now hidden from 25 the view seen in reflection from the first side by the application of the partially opacifying layer 16. The partially opacifying layer 16 is also applied in a way as to provide a shadow image. This may be in the form of a margin outside the outline of the window shape formed by partially opacifying layer 14 and/or may provide a multi-tone shadow image when viewed in transmission. 30 Each of the partially opacifying layers 12, 14 and 16 preferably comprises a pigmented coating. In a preferred embodiment the pigmented coating is a white opacifying ink. For example, the pigmented coating may be formed from a white pigment, such as titanium dioxide, dispersed within a binder or carrier. However, 13 other coloured pigments may be used. The binder or carrier may be a polymeric material. The partially opacifying layers may be applied in a printing process, preferably by Gravure printing, though other printing methods may be used. Figure 5a corresponds to Figure 4a with a coloured layer 18 applied on the 5 third partially opacifying layer 16. The coloured layer 18 may be formed from a permanently coloured ink or a translucent coloured ink. The coloured layer 18 is preferably applied in a printing process, such as a Simultan offset printing process, though other methods of printing, such as screen printing or intaglio printing may be used. Figure 5b shows the resulting image seen in reflection 10 from the first side, where the coloured layer 18 forms a background for the images of the frog and single gum leaf produced by the window area 15, and the partial branch shape 19 produced by the opacifying layers . When viewed in transmission from the opposite side of the transparent plastics substrate 10, the colour of the layer 18 may be seen through the partially opacifying layers, though 15 will not be as intense as when viewed in reflection from the first side. In reflection a shadow image effect results from a combination of multiple tones from the transparent area (frog and single gum leaf shape), partial opacifying layers 12, 14, 16 (partial branch shape) and the pattern of the coloured printed layer 18 (shown as concentric circles in figure 5b). 20 Figure 6a corresponds to Figure 5a, with a partially opacifying layer 22 applied on the opposite, second side of the transparent substrate. The partially opacifying layer 22 does not entirely cover the transparent plastics material 10, leaving a 'window' area 23. In Figure 6b, the 'window' area 23 is of similar shape to the 'window' area 15 formed by the opacifying layer 14 in that it is in the shape 25 of a frog, but with the single leaf part of the image formed by 'window area 15 omitted. The opacifying layers 14 and 22 are applied in such a manner that the 'frog' parts of the images formed by the window areas 15 and 23 substantially coincide to form a fully transparent window. Figure 7a corresponds to Figure 6a with an additional partially opacifying 30 layer 24 applied to the second side. This partially opacifying layer 24 may cover the same or a different area as partially opacifying layer 22. As shown in Figure 7b, the partially opacifying layer 24 covers almost the same area as partially opacifying layer 22 and is omitted in area 25 which substantially corresponds to 14 window area 23 leaving the shape of the image (frog) uncovered. The partially opacifying layer 24 is preferably applied so as to provides a small margin outside the outline of the window shape formed by partially opacifying layer 22. Figure 7b shows the image in reflection from the second side which consists of substantially 5 the same frog-shaped 'window' to the one shown in Figure 6b, though the image may have a small marginal area around the window which is only covered by partially opacifying layer 22, and not by partially opacifying layer 24. Another coloured layer 26 is now applied to the second side as seen in the sectional view of Figure 8a. The coloured layer 26 covers a similar area to the 10 opacifying layer 24 except for a small area 27 around the window areas 23 and 25. Figure 8b now shows the view in reflection from the second side with a multi toned shadow image, formed from combination of a frog-shaped 'window' area 23, a white margin around the frog shape formed from the partially opacifying layers 22 and 24 and the coloured printed layer 26 which may be applied in a 15 pattern (the concentric circles shown in Figure 8b). Figure 9a, 10a and 11a each show sectional views corresponding to Figure 8a, but with a security layer 28 now applied to the second side. The security layer 28 covers part of the coloured layer 26 and partially covers the window areas 23, 25, 27 leaving a part of the window areas uncovered which still 20 remains as a fully transparent window area 29. The security layer is preferably applied in the shape of a distinct image, (a lizard in the particular embodiment shown in Figure 9b). The security layer may cover the whole of the window areas 23, 25, 27, but preferably covers only a part of or parts of the window areas. As shown in Figure 9b, the security layer 28 covers the body part of the frog image 25 formed by the window areas 23, 25, 27 but the legs and eye of the frog are left uncovered. Figure 9b shows a final view in reflection from the second side. The security layer 28 in this embodiment is preferably an optically variable patch which includes optically variable inks and a magnetic image. Such a patch may 30 be obtained from SICPA HOLDING SA as sold under their trade mark SPARK OVITM. The final view in reflection from the second side shown in Figure 9b is an aesthetically pleasing complex image formed the combination of the lizard shaped security layer 28, partial frog shaped area formed from the window areas 15 of the partially opacifying layers 22 and 24 and the background pattern of the coloured layer 26. Figure 10b shows a final view in reflection from the first side. Part of the security layer 28 can be seen through window area 15 of the uncovered 5 transparent plastics material 10. This is shown in Figure 10b as the body of the frog. The fully transparent window area 29 forms the legs and eyes of the frog image and the single leaf, The total view shows a complex coloured shadow image formed from the combination of the partially opacifying layers 12, 14 and 16, the part 28a of the security layer 28 visible through the window area 15, the 10 image of the branch formed by partially opacifying layer 14, and the background pattern of the coloured layer 18. This view is a complex graphic that is very different from the view in reflection from the first side shown in Figure 9b, increasing the difficulty of reproduction. Figure 11 b shows the final view of the composite window security device 15 as seen in transmission. Here an extremely complex shadow pattern is shown that contains multiple colours and tones in opacity formed from the various partially opacifying layers 12, 14, 16, 22 and 24, coloured layers 18 and 26 and different parts 28a and 28b of the security layer 28. In particular, the outline of the gum branch with multiple leaves and gumnuts that is hidden from view in 20 reflection by the partially opacifying layers can now be seen as a shadow image, providing an additional level of security. Additionally the entire outline of both the frog and lizard can now be viewed, with part 28a of the security layer forming the body parts of both the frog and lizard, and the remaining part 28b of the security layer forming the head, legs and tail of the lizard as a shadow image 25 The combination of the layers of the composite window security device produce substantially different images from the first and second sides of the transparent plastics material in reflection and in transmission, such as illustrated in Figures 9b-1 1 b. This provides a complex and aesthetically pleasing security document or device that is also difficult to reproduce or counterfeit. 30

Claims (5)

1. A security document or device including at least one area formed from a transparent plastics material, at least one partially opacifying layer applied to a first side of the transparent plastics material, at least one partially opacifying layer 5 applied to the opposite second side of the transparent plastics material, at least one coloured layer on one or both sides of said first and second sides of the transparent plastics material, and at least one security layer applied on one or both sides of the transparent plastics material, wherein the partially opacifying layers on both sides of the substrate are omitted in 10 at least one area to form a window in the security document, the security layer extends at least partially over the window and into the surrounding region of the transparent plastics material covered by at least one of the partially opacifying layers, and the partially opacifying layers, at least one of the coloured layers, the 15 window area and the at least one security layer cooperate to produce a first image visible in reflection from the first side of the transparent plastics, a second image visible in reflection from the second side of the transparent plastics material and a third image visible in transmission from both sides of the transparent plastics material. 20

2. A method of forming a security document or device including the steps of: providing a transparent plastic material, applying at least one partially opacifying layer to a first side of the transparent plastics material, applying at least one partially opacifying layer to the opposite second side 25 of the transparent plastics material, applying at least one coloured layer on one or both sides of said first and second sides of the transparent plastics material, and applying at least one security layer on one or both sides of the transparent plastics material, wherein 17 the partially opacifying layers on both sides of the substrate are omitted in at least one area to form a window in the security document, the security layer extends at least partially over the window and into the surrounding region of the transparent plastics material covered by at least one of 5 the partially opacifying layers, and the partially opacifying layers, at least one of the at least one coloured layer, the window area and the at least one security layer cooperate to produce a first image visible in reflection from the first side of the transparent plastics, a second image visible in reflection from the second side of the transparent plastics 10 material and a third image visible in transmission from both sides of the transparent plastics material.

3. A security document or device or a method according to claim 1 or 2 wherein the at least one security layer is selected from an optically variable layer, a reflective metallic layer, a layer containing a magnetic image, and an optically 15 variable layer containing a magnetic image.

4. A security document or device or a method according to any of the previous claims including a plurality of opacifying layers applied to at least one side of the transparent plastics material and wherein at least one of said plurality of partially opacifying layers covers more or less of the transparent plastics 20 material than another of said plurality of partially opacifying layers.

5. A security document or device or a method according to any of the previous claims according to any of the previous claims wherein the first image visible in reflection from the first side of the transparent plastics, the second image visible in reflection from the second side of the transparent plastics 25 material, and the third image visible in transmission from both sides of the transparent plastics material are all different. RESERVE BANK OF AUSTRALIA WATERMARK PATENT AND TRADE MARKS ATTORNEYS 30 UIP1299AUO