Security devices and method of manufacture thereof
AssigneeDe La Rue International Limited
InventorsJohn Godfrey, Rebecca Locke
Life of this patent
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Abstract
A security device is provided, comprising one or more surface relief structure(s), each formed of one or more cured material(s), the surface relief structure(s) being disposed on a substantially flat substrate and defining a plurality of raised elements spaced from one another, the raised elements corresponding to elements of an image, whereby the plurality of raised elements varies across the surface relief structure(s) so as to exhibit a multi-tonal version of the image. Methods of manufacturing such devices are also disclosed.
Claims20
A security device, comprising one or more surface relief structure(s), each formed of one or more cured material(s), the surface relief structure(s) being disposed on a substantially flat substrate and defining a plurality of raised elements spaced from one another, the raised elements corresponding to elements of an image, whereby the plurality of raised elements varies across the surface relief structure(s) so as to exhibit a multi-tonal version of the image, wherein:
- the image is a macro image;
- the raised elements have heights in the range of 20 μm to 100 μm;
- for at least one of the surface relief structure(s) the raised elements are joined by a base layer of the cured material(s), the base layer having a lower height than the raised elements such that there is a contrast between the raised elements and the base layer, wherein a ratio of the height of at least one raised element to the height of the base layer joining the raised element to an adjacent raised element is at least 10:1 and no greater than 400:1;
- and
- the raised elements provide a tactile feature of the security device.
A method of manufacturing a security device, comprising forming one or more surface relief structure(s) on a substantially flat substrate, each formed from one or more curable material(s) and curing the material(s), the surface relief structure(s) defining a plurality of raised elements spaced from one another, the raised elements corresponding to elements of an image, whereby the plurality of raised elements varies across the surface relief structure(s) so as to exhibit a multi-tonal version of the image, wherein:
- the image is a macro image;
- the raised elements have heights in the range of 20 μm to 100 μm;
- for at least one of the surface relief structure(s) the raised elements are joined by a base layer of the cured material(s), the base layer having a lower height than the raised elements such that there is a contrast between the raised elements and the base layer, wherein a ratio of the height of at least one raised element to the height of the base layer joining the raised element to an adjacent raised element is at least 10:1 and no greater than 400:1;
- and
- the raised elements provide a tactile feature of the security device.
Dependencies are inferred from the claim text.