For manufacturers it is increasingly important to be able to protect their products from copying or counterfeiting, and for consumers it is important that they can rely on the authenticity of products. Images and holograms are widely used for this purpose, as they are difficult to reproduce.

Images or holograms have gained wide acceptance for protecting products against counterfeiting as images and holograms are difficult to reproduce.

The applicant's prior application WO 02/02352 discloses a metal container holding a surface relief and a method for replicating and protecting a surface relief. This metal container is a great leap forward in assuring authenticity of a product, however there is an ever-increasing need for even more sophisticated indication of authenticity of a product and protection against counterfeiting.

Prior art teaches how to provide different kinds of images and holograms on articles to protect against counterfeiting.

US 2002/0044313 describes an optical feature for documents of value and having at least one dual-channel hologram for the holographic reconstruction of different images from different directions of gaze, in which different regions of the hologram are associated with the different channels and the regions of the hologram reconstructing the respective image under incident light have sub-regions which do not take part in the image reconstruction.

EP 0 346 869 discloses a method of forming a holographic device by forming a first hologram on a major surface of a substrate, then desensitizing said first hologram to prevent interaction with a second subsequently formed hologram, and the forming the second hologram conterminous with said first hologram, whereby the holograms of said device are bonded together absent an additional adhesive layer.

WO 02/097537 relates to a method for producing an optical element, preferably a security feature, according to which a film with a first embossed hologram is provided in an embossed layer, and a second embossed hologram is embossed into the same embossed layer whereby the embossed hologram is partially replaced by the second embossed hologram.

WO 97/19820 relates to an optical carrier which is in the form of a composite laminate with a carrier foil and which has microscopically fine relief structures, the carrier foil being approximately transparent for light in a predetermined spectral range, and microscopically fine relief structures are formed into the underside of the carrier foil. The underside is coated with a base layer whose refractive index differs from the refractive index of the carrier foil in at least a portion of the electromagnetic spectrum so that the relief structures on the underside at least partially reflect and diffract the light which has penetrated into the composite laminate. The top side of the carrier foil is provided with optically effective structures which allow light impinging on the top side to penetrate at least partially in the composite laminate and the thickness of the carrier foil is at least 20 micrometres.

US 2001/002653 describes a packaging for sports equipment comprising an enclosure and a hologram formed on at least a portion thereof for diffusely reflecting incident light. A marking layer may be formed on a first hologram by laminating one or more second hologram layers thereon.

EP 0 328 086 describes an article comprising a continuous unperforated sheet carrying a hologram or diffraction pattern including a number of discontinuous areas, said areas being characterised by reconstructing a recognisable light pattern by diffraction of incident light therefrom. A first hologram formed in a non-continuous areas across a sheet contains a first image, and a second hologram containing a second image is formed in non-continuous areas across said sheet that are non-overlapping with the first hologram areas.

It is an object of the present invention to provide a method for producing a composite surface of an article and an article having an improved protection against copying.

A first aspect of the invention relates to a method for producing a composite surface of an article comprising the steps of:

providing a substrate, - providing a first structure on a surface area of the substrate, applying a layer of at least semi-transparent coating covering the first structure, providing a second structure into a surface area of the coating above said first structure so as to cover at least a part of said first structure, and

wherein the second structure is adapted to be shiftable between an active state at least partially hiding the first structure, and an inactive state at least partially revealing the first structure.

The first structure may be provided as a separate foil on the substrate, according to an embodiment, however, the first structure is provided by embossment of the substrate. By embossing the first structure directly into the surface of the substrate, a separate step of achieving and placing the structure on the substrate is avoided, and there is no risk that the structure is displaced during production of the composite surface.

As an example, the substrate may be the material of which a product is made, such as the metal sheet for a container, and by this method the first structure may be provided on the surface of the material before the container is formed into its final form. Thus, a much more precise placing of the first structure on the final product is obtained by this method. Furthermore, as the first structure is provided before the final shaping of the product, products may be provided having a complex outer geometry while still having the first structure placed on a preferred location on the surface of the product. Especially, it is an advantage on products being unrounded and having inwardly contours, such as lids or bottom or sidewall parts of containers.

The article may be adapted to be attached on a product, such that the article for example may be a tag attached to a product or to the product packaging, which may be made o-f any material, such as metal, plastic, cardboard or composite materials.

The first structure may comprise images (such as pattern, logos or figures), holograms- , reliefs, decorations or prints, such as text, or any combination of these. Preferably, the- first structure is a hologram.

The second structure may comprise images (such as pattern, logos or figures), hologra ms, reliefs, decorations, such as text, or any combination of these.

The substrate may be made of any suitable material, such as plastic, cardboard or composite materials, according to an embodiment, however, the substrate is metal, which is a durable and widely used material for containers, such as cans for food. A metal substrate is particularly advantageous when the first structure is produced by embossment.

The coating may be a transparent polymer, such as a foil or the like, according to an embodiment, however, the coating is a semi-transparent lacquer, which may be coloured.

The second structure may be shifted into its inactive state by applying a substance to t he surface of the structure so as to neutralise the structure of the surface and make said First structure visible through said layer of coating, and the second structure is shifted into i ts active state by removing said substance from the surface of the structure.

The substance may comprise any kind of grease or sebum.

The composite surface may comprise further layers of coating, one or more of which m ay comprise images or holograms or reliefs or decorations or prints, such as text.

The coating may be applied to the substrate by rolling, laminating or spraying or other commonly used lacquering techniques.

A second aspect of the invention relates to an article having a composite surface comprising a substrate having a first structure on a surface area thereof, the first structure being covered by a layer of at least semi-transparent coating, said layer having a second structure incorporated in a surface area thereof and hiding at least a part of said first structure, and wherein the second structure is adapted to be shiftable between an actKxe state at least partially hiding the first structure, and an inactive state at least partially revealing the first structure.

The first structure may comprise images (such as pattern, logos or figures), holograms, reliefs, decorations or prints, such as text, or any combination of these. Preferably, the first structure is a hologram.

The second structure may comprise images (such as pattern, logos or figures), holograms, reliefs, decorations, such as text, or any combination of these.

The first and second structure may be embossed into the surface of the substrate and coating layer, respectively.

By providing a first structure protected by a coating and then providing the surface of the coating with a second structure, the authenticity of the article is assured to a very high degree, as this article is very difficult to copy.

To further increase the protection against copying, the second structure is adapted to be shiftable between an active state at least partially hiding the first structure, and an inactive state at least partially revealing the first structure. This means that the first structure would normally be hidden at a first glance, but can be revealed by active manipulation of the second structure. Hence the copier may not notice the first structure and hence produce an article without the first structure.

According to an embodiment, the second structure is adapted to be shiftable to an inactive state by applying a substance to a surface area of the second structure, and adapted to be shiftable to the active state by removing the substance from the structure.

Thus, when applying substance to the surface area of the second structure, the structure is neutralised such that the area containing the structure becomes transparent (the reflecting effect of the structure is removed), and thus the first structure on the substrate becomes visible for the user through the layer of coating.

The substance may be any kind of grease, or it may sebum, which may be supplied to the structure by rubbing on the surface with a finger.

The second structure becomes active again when removing the substance from the structure, e.g. by washing the structure.

In another embodiment, the substance may be applied by a label being attached to the layer of coating, so that the second structure can be shifted into its active state by removing said label from the structure. In a still further embodiment, the substance may applied to the second structure by applying an aqueous liquid to the structure and subsequently harden it, said hardened liquid being detachable from the structure. The aqueous liquid may comprise a polymer liquid that hardens into a film.

The substrate and coating layer may of course comprise more than one first and second structure, respectively.

According to a third aspect, the present invention relates to a method for producing a composite surface of an article comprising the steps of:

providing a layer of at least semi-transparent material, providing a first and second structure on opposite sides of said semi-transparent layer, respectively, the second structure overlapping at least a part of the first structure, - applying a substrate to the semi-transparent layer covering at least the first structure, and

wherein the second structure is adapted to be shiftable between an active state at least partially hiding the first structure, and an inactive state at least partially revealing the first structure.

The semi-transparent layer comprises both the first and second structure on its opposite sides, and in order to see the first structure through the layer, the first structure is applied with a substrate for obtaining its "visual effect".

The substrate may for example be the material of which a product is made, such as the metal sheet for a container, and by this method a container is protected against counterfeiting simply by attaching said layer to the sidewall of the container.

The substrate may be laminated or sprayed or rolled on to the semi-transparent layer.

The invention according to the third aspect may comprise any of the features and steps mentioned above in connection with the first and second aspects.

According to a fourth aspect, the present invention relates to an article having a composite surface comprising a layer of at least semi-transparent material having a first and a second structure on opposite sides, respectively, the second structure overlapping at least a part of the first structure, a substrate covering at least said first structure, and

wherein the second structure is adapted to be shiftable between an active state at least partially hiding the first structure, and an inactive state at least partially revealing the first structure. The invention according to the fourth aspect may comprise any of the features mentioned above in connection with any of the first, second and third aspects.

According to any of the four aspects, the first and second structure may in combination define a common image or decoration or text. Thus, the first structure may for example show a horse and the second structure may show a rider, so that the common image is a horse with a rider on its back. Alternatively, the first structure could show a first part of a word or sentence and the second structure could then show the remaining part thereof. Thus, the first and second structure provides a "synergy-effect".

Though the main purpose of the methods and articles according to the invention is to improve the protection against counterfeiting, it may also be useful in other relations. For example it may be used in toys for children, games such as board games. It could also be used in Advent Calendars, where the "windows" may be composed by said coating layer, and thus in order to "open" the calendar, the child just has to inactivate the second structure.

For the purpose of avoiding counterfeiting, a product may be delivered with the second structure in its active state hiding the first structure, so that the user must inactivate the second structure to be sure that the product is original. However, the second may be in its inactive state when the user receives the product.

The present invention will now be described by way of example with reference to the drawing, in which

Fig. 1 is a sketch of a cross section of a composite surface according to the invention.

Fig. 2 is an enlarged surface portion of Fig. 1,

Fig. 3 corresponds to Fig. 2.

In Fig. I a cross-section of a composite surface 1 of an article can be seen. The composite surface 1 comprises a substrate 2, e.g. of metal, provided with a first structure 4 on a surface thereof. The first structure 4 may be provided by embossment directly into the surface of the substrate 2. A layer 3 of semi-transparent coating is provided on the surface of the substrate 2 holding the first structure 4. The layer 3 protects the first structure 4 against damage.

The surface of the layer 3 is provided with a second structure 5 incorporated in a surface area thereof. The second structure 5 has an extent and placing to substantially cover the first structure 4.

Fig. 2 illustrates the surface of layer 3 at the second structure 5. As can be seen, the second structure 5 comprises a three-dimensional pattern on the surface of the layer 3. In Fig. 3, which corresponds to Fig. 2, three-dimensional pattern of the second structure 5 is filled by grease 6, such as sebum. Hereby the second structure 5 is inactivated in that diffraction of light in the pattern no longer takes place, so it is possible for the observer to see the first structure 4.