Security elements and methods of their manufacture

Patent metadata

Field	Value
Publication number	US-10252562-B2
Application number	US-201515111691-A
Country	US
Kind code	B2
Filing date	Jan 15, 2015
Priority date	Jan 20, 2014
Publication date	Apr 9, 2019
Grant date	Apr 9, 2019

Abstract

A security element including substrate on which is disposed: in first area, a first optically variable device including a diffractive or reflective relief structure and reflection enhancing material following contours of relief structure; and, in second area, a second optically variable device including an iridescent amplitude interference material. First optically variable device is constituted by a plurality of sub-areas arranged in cyclically repeating sequence along predetermined direction of the security element, the plurality of sub-areas collectively forming first area. Relief parameters of diffractive or reflective relief structure vary from one sub-area to next within each repeat cycle whereby, at any viewing angle, each sub-area within any repeat cycle exhibits different diffractive color or reflected intensity from those of other sub-areas within same repeat cycle, so, when device is tilted, different diffractive colors or reflected intensities appear to move from one sub-area to next within each repeat cycle along predetermined direction.

First claim

The invention claimed is:

1. A security element comprising a substrate on which is disposed:
in a first area, a first optically variable device comprising a diffractive or reflective relief structure and a reflection enhancing material following contours of the relief structure; and
in a second area, a second optically variable device comprising an iridescent amplitude interference material;
wherein the first optically variable device is constituted by a plurality of sub-areas arranged in a cyclically repeating sequence along a predetermined direction of the security element, the plurality of sub-areas collectively forming the first area, relief parameters of the diffractive or reflective relief structure varying from one sub-area to the next within each repeat cycle, wherein each repeat cycle of the relief parameters includes at least three sub-areas, and whereby, at any one viewing angle, each sub-area within any one repeat cycle exhibits a different diffractive colour or reflected intensity from those of the other sub-areas within the same repeat cycle, and such that, when the device is tilted in a direction parallel to the predetermined direction, different diffractive colours or reflected intensities appear to move from one sub-area to the next within each repeat cycle along the predetermined direction.

2. A security element according to claim 1 , wherein the first and/or second area comprising the first or second optically variable device respectively is elongate and extends along the predetermined direction of the security element.

3. A security element according to claim 1 , wherein the security element is elongate in the predetermined direction.

4. A security element according to claim 1 , wherein the first optically variable device comprises one of:
a diffractive relief structure, the relief structure having a pitch which varies from one sub-area to the next, the pitch within each sub-area lying in the range 0.5 microns to 10 microns; or
a reflective relief structure, the relief structure comprising an array of reflective facets, the angle between the facets and the plane of the device varying from one sub-area to the next.

5. A security element according to claim 1 , wherein the first optically variable device is configured such that, when the device is tilted in the direction perpendicular to the predetermined direction, the different diffractive colours or reflected intensities appear to move from one sub-area to the next within each repeat cycle along the predetermined direction.

6. A security element according to claim 5 , wherein the first optically variable device comprises one of:
a diffractive relief structure, the orientation of the relief structure in the plane of the device varying from one sub-area to the next; or
a reflective relief structure, the relief structure comprising an array of reflective facets, the orientation of the facets in the plane of the device varying from one sub-area to the next.

7. A security element according to claim 1 , wherein each sub-area has the form of a line, band, geometrical shape, symbol or alphanumeric character.

8. A security element according to claim 1 , wherein a plurality of adjoining sub-areas collectively form a geometrical shape, symbol or alphanumeric character.

9. A security element according to claim 1 , wherein at least some of the sub-areas abut one another along the predetermined direction, the boundary between one sub-area and the next lying substantially perpendicular to the predetermined direction.

10. A security element according to claim 1 , wherein the sub-areas are each of substantially the same size and shape.

11. A security element according to claim 1 , wherein the size and/or shape of the sub-areas varies cyclically along the predetermined direction.

12. A security element according to claim 1 , wherein the diffractive or reflective relief structure is disposed in both the first and second areas of the element, and is substantially concealed in the second area of the element by an overlying light absorbing material.

13. A security element according to claim 1 , wherein the iridescent amplitude interference material is disposed in both the first and second areas of the element, and is substantially concealed in the first area of the element by light diffracted or reflected from the diffractive or reflective relief structure.

14. A security element according to claim 1 further comprising one or more substantially transparent regions in which the reflection enhancing material and light absorbant material are absent, the substantially transparent regions defining a decorative pattern or negative indicia.

15. A security element according to claim 1 wherein the iridescent amplitude interference material comprises any of: a thin film interference structure, interference pigments, iridescent pigments, pearlescent pigment, mica pigments, liquid crystal (LC) pigments and photonic crystals.

16. A security element according to claim 1 wherein the reflection enhancing material is arranged in accordance with a screened or half-tone pattern, or is semi-transparent.

17. A security element according to claim 1 , wherein the reflection enhancing material is electrically conductive and includes at least one continuous path from one end to the other of the security element, at least a portion of the continuous path being concealed by the iridescent amplitude interference material.

18. A security element according to claim 1 , further comprising a layer of magnetic material, the magnetic material being concealed by the reflection enhancing layer and/or the iridescent amplitude interference material.

19. A security article, comprising a security element according to claim 1 .

20. A security document comprising a security element according to claim 1 applied to or incorporated in the security document, wherein the security document is preferably a banknote, polymer banknote, passport, identification document, passport, visa, cheque or certificate.

21. A security element comprising a substrate on which is disposed, in at least a region of the security element:
a diffractive or reflective relief structure present at least in first partial areas of the region in accordance with a first pattern;
a reflection enhancing material provided in the first partial areas of the region in accordance with the first pattern, disposed on and following contours of the diffractive or reflective relief structure;
a light absorbing material provided in second partial areas of the region in accordance with a second pattern;
one or both of the first and second patterns comprising a plurality of discrete pattern elements; and
a non-opaque layer of iridescent amplitude interference material at least over the second partial areas of the light absorbing material;
wherein the first and second patterns are in register with one another and each switches repeatedly from one side to the other of a straight line defining an axis of the security element along the same portion of the line in an alternating manner with the other pattern, whereby in the areas of the reflection enhancing layer defined by the first pattern, visual effect of the diffractive or reflective relief structure is visible, and in the areas of the light absorbing material defined by the second pattern, visual effect of the non-opaque iridescent amplitude interference material is visible, such that the two visual effects are exhibited on opposite sides of the straight line at any one location and

Assignees

• De La Rue Int Ltd

Inventors

• Holmes Brian William

Classifications

• B41M3/14 Primary

  Security printing {(securities B42D25/29)} · CPC title

• B42D25/355

  Security threads · CPC title

• B41M3/148

  Transitory images, i.e. images only visible from certain viewing angles · CPC title

• B42D25/324 Primary

  Reliefs · CPC title

• B42D25/40

  Manufacture · CPC title