Abstract: An optically variable security device comprising a thin film reflection filter structure (23) which exhibits a first optically variable effect; and a relief structure (20) on or in the thin film reflection filter structure which exhibits a second optically variable effect.

Abstract: A security device has a substrate formed with a surface relief defining an optically variable effect generating structure. At least two different reflection enhancing materials are provided on, or on the same side of, substrate with respect to the surface relief, whereby the optically variable effect can be viewed against a background defined by the reflection enhancing materials.

Abstract: A security device comprising a substrate (1) formed with a surface relief (2) defining an optically variable effect generating structure. At least two different reflection enhancing materials (4, 6) are provided on, or on the same side of the substrate (1) with respect to the surface relief (2), whereby the optically variable effect can be viewed against a background defined by the reflection enhancing materials.

Abstract: A security device comprises an optically variable effect generating structure (3,4). An obscuring layer (7) is located, in use, between the optically variable effect generating structure and a substrate (8) to which the device is secured. A color layer (6) is also included which exhibits one or more predetermined colors when viewed under certain viewing conditions from the side of the device remote from the obscuring layer. The obscuring layer (7) is substantially opaque under the said certain viewing conditions.

Abstract: An optically variable security device comprising a thin film reflection filter structure (23) which exhibits a first optically variable effect; and a relief structure (20) on or in the thin film reflection filter structure which exhibits a second optically variable effect.

Abstract: A method of manufacturing a laminate structure for use in a security thread or tape comprises: i) providing a first structure (1) having a flexible carrier (2) supporting an optically variable effect structure (4-6); ii) adhering the first structure (1) to a flexible substrate (9) with the optically variable effect structure (4-6) between the carrier and the substrate; iii) removing the carrier (2); iv) permanently bonding the carrier (2) to the resulting laminate to generate a final laminate structure; and, v) slitting the laminate structure from step iv) into at least two lengths.

Abstract: A method of manufacturing a security device, the method comprising providing a radiation curable material on a shrinkable substrate; imparting an optically variable effect structure on or into the radiation curable material; and curing the material so that it retains the optically variable effect structure.

Abstract: A tamper indicating security item such as a shrink wrap seal comprises a substrate including an optically variable effect generating structure such as an embossed hologram. Each surface of the substrate carries an adhesive having a strength such that after the substrate has been adhered to a surface it cannot be removed without damaging the optically variable effect generating structure.

Abstract: A method of enhancing an image (11) provided by thermoplastic marking material on a substrate (4) which material can be thermally activated to take on adhesive properties. The method comprises bringing a transfer medium (7) into contact with the substrate (4) carrying the marking material, the transfer medium including a carrier (3) and a transferable layer (15, 16), the transferable layer being positioned in use between the carrier and the substrate: thermally activating the adhesive property of the marking material; and separating the carrier (13) and substrate (4) whereby areas of the transferable layer containing the activated marking material remain on the marking material, characterized in that the transferable layer exhibits or generates a visible pattern.

Abstract: The article includes a substrate which is composed of a single ply that contains both a structure for generating a viewable optically variable effect, such as a hologram, and carries an indicia receptive coating. The indicia receptive coating covers the single ply such that at least part of the optically variable effect is visible. The indicia receptive coating may receive printed indicia such as security indicia, alphanumeric character shapes, symbols, and bar codes. The article with the single ply that contains viewable optically variable effect and also carries the printed indicia, is more tamper resistant than previous identification documents. It is very difficult, if not impossible, to alter the printed indicia without also altering the structure that generates the viewable optically variable effect or vice versa.

Abstract: A tamper resistant security seal is a laminated tape having a transparent carrier layer (2); an optical, diffraction pattern defining layer (3,4); and an adhesive layer (6) for adhering the tape to a substrate. The optical pattern, such as a hologram, defined by the optical pattern defining layer is visible from outside the laminate. The optical diffraction pattern defining layer (3) is formed by a polymeric layer permanently bonded to the transparent carrier layer which, when heated, causes the diffraction pattern to undergo an irreversible change. The adhesive is a pressure sensitive adhesive. An additional removable support layer may be provided on the carrier. The laminate is constructed so that a reduction in temperature below 0.degree. C. will cause an irreversible change in the diffraction pattern, or is such that subsequent to such a temperature reduction, attempted removal of the tape from a substrate will cause an irreversible change in the diffraction pattern.

Abstract: An optical security device for use on a security article comprises a number of layers including an optically diffracting layer and an at least partially reflective layer which together generate a first image. A non-optically diffracting second image is provided within the device in association with the first image.

Abstract: A security card blank comprises a plurality of superposed layers (5,5',6,7,8,9) including a metallic layer (5,5'). The metallic layer comprises any radiation absorbent, metal, metalloid, or their alloys or derivatives, such as oxides or sulphides. The metallic layer (5,5') is positioned within the card blank and is imageable only under the influence of high intensity radiation to produce a security card. After imaging, at least part of the imaged metallic layer is detectable from outside the card.