Security devices

Patent metadata

Field	Value
Publication number	US-9902186-B2
Application number	US-201314412058-A
Country	US
Kind code	B2
Filing date	Jul 5, 2013
Priority date	Jul 6, 2012
Publication date	Feb 27, 2018
Grant date	Feb 27, 2018

Abstract

A security device is provided including a first pattern of elements and a second, overlapping, pattern of elements spaced by a transparent layer, the first and second patterns in combination obstructing the passage of light transmitted to a viewer through the device to a varying degree depending on the viewing position. The first and second patterns of elements are configured such that a first region of the device exhibits a maximum change in the degree of obstruction when the device is tilted relative to the viewer about a first tilt axis, and a second region of the device exhibits a maximum change in the degree of obstruction when the device is tilted relative to the viewer about a second tilt axis which is not parallel to the first tilt axis.

First claim

The invention claimed is:

1. A security device comprising
a first pattern of elements and
a second, overlapping, pattern of elements spaced by a transparent layer, the first and second patterns in combination obstructing the passage of light transmitted to a viewer through the device to a varying degree depending on the viewing position, wherein
the first and second patterns of elements are configured so as to define at least three regions of the device, constituting a first group of regions, each region exhibiting a maximum degree of obstruction when observed by a viewer from at least one maxima viewing position, and a minimum degree of obstruction when observed by a viewer from at least one minima viewing position, the at least one maxima viewing position and the at least one minima viewing position constituting a set of peak viewing positions for each region,
the sets of peak viewing positions associated with each of the regions of the first group respectively are different from one another,
at least when viewed from a position away from the normal, each of the at least three regions of the first group exhibits a different degree of obstruction, and
the lateral offset of the first pattern relative to the second pattern is different in each of the at least three regions of the first group, whereby when viewed from the normal viewing position, contrast is exhibited between each of the regions of the first group and when the tilt angle is changed relative to the viewer along at least one tilt direction, the contrast exhibited between each of the regions of the first group changes.

2. A security device according to claim 1 , wherein the first and second patterns are configured such that, as the viewing position is changed, a respective maxima viewing position or a respective minima viewing position for each of the at least three regions of the first group is reached in the same order as that in which the corresponding regions are arranged spatially across the device in a first continuous direction.

3. A security device according to claim 2 , wherein the regions of the first group are arranged spatially on the device adjacent one another, such that as the device is tilted and/or rotated, adjacent regions exhibit their maximum or minimum obstruction in sequence.

4. A security device according to claim 1 , wherein the regions of the first group are adjacent one another and the degrees of obstruction exhibited by the regions of the first group at least when viewed from a static position away from the normal increase from one region to the next adjacent region in series such that in combination the regions exhibit a spatially graduated degree of obstruction across the device.

5. A security device according to claim 1 , wherein each of the at least three regions of the first group exhibits a maximum rate of change in the degree of obstruction with tilt angle when the device is tilted relative to the viewer about different respective tilt axes, whereby as the tilt direction is changed relative to the viewer, a different one of the at least three regions of the first group exhibits its maximum or minimum degree of obstruction in turn.

6. A security device according to claim 5 , wherein the tilt axes about which each respective region of the first group exhibits its maximum rate of change in degree of obstruction with tilt angle lie at angles which successively increase relative to a reference direction from one region to the next region of the first group in series, whereby as the tilt direction is changed relative to the viewer, regions of the first group exhibit their maximum or minimum obstruction in sequence along a continuous direction.

7. A security device according to claim 1 , wherein at different tilt angles along the tilt direction parallel to the offset direction, different ones of the at least three regions of the first group exhibit their maximum obstruction.

8. A security device according to claim 1 , wherein the lateral offset between the first and second patterns in a constant offset direction increases successively from one region to the next region of the first group whereby, at any viewing position, in combination the regions of the first group exhibit a spatially graduated degree of obstruction across the device and as the tilt angle is changed along the tilt direction parallel to the offset direction, regions of the first group in series along a continuous direction exhibit their maximum obstruction in sequence.

9. A security device according to claim 8 wherein the regions of the first group are adjacent one another.

10. A security device according to claim 1 , wherein in only one of the first and second patterns, the elements in the second and third regions of the first group are laterally shifted relative to those in the first region to provide the change in lateral offset between regions.

11. A security device according to claim 1 , wherein in each of the first and second patterns, the elements in the second and third regions of the first group are laterally shifted relative to those in the first region to provide the change in lateral offset between regions, the lateral shift of the elements in the first pattern being opposite in direction to the lateral shift of the elements in the second pattern.

12. A security device according to claim 11 , wherein at least a pair of the at least three regions of the first group have a lateral offset substantially equal in magnitude but opposite in direction, whereby when the device is viewed from the normal position, the pair of regions exhibits substantially equal degrees of obstruction whilst when the device is tilted relative to the viewer along the tilt direction parallel to the offset direction, one of the pair of regions exhibits an increased degree of obstruction whilst the other of the pair of regions exhibits a reduced degree of obstruction.

13. A security device according to claim 1 , wherein the first and second patterns of elements are further configured so as to define a second group of regions comprising at least two further regions of the device, each region of the second group exhibiting a maximum degree of obstruction when observed by a viewer from at least one maxima viewing position, and a minimum degree of obstruction when observed by a viewer from at least one minima viewing position, the at least one maxima viewing position and the at least one minima viewing position constituting a set of peak viewing positions for each region, and wherein the sets of peak viewing positions associated with each of the regions of the second group respectively are different from one another, the first and second patterns being configured such that, as the viewing position is changed, the second group of regions displays a change in obstruction levels which is different from that exhibited by the first group of regions.

14. A security device according to claim 13 , wherein the lateral offset of the first pattern relative to the second pattern is different in each of the at least three regions of the first group, whereby when viewed from the normal viewing position, contrast is exhibited between each of the regions of the first group and when the tilt angle is changed relative to the viewer along at least one tilt direction, the contrast exhibited between each of the regions of the first group changes; and
wherein the lateral offset of the first pattern relative to the second pattern is different in each of the at least two regions of the second group, whereby when viewed from the normal viewing position, contrast is exhibited between each of the regions of the second group and when the tilt angl

Assignees

• De La Rue Int Ltd

Inventors

• Whiteman Robert
• Smith Alice
• Lister Adam

Classifications

• B42D25/387

  absorbing or reflecting ultraviolet light · CPC title

• B42D25/435

  using electromagnetic radiation, e.g. laser · CPC title

• B42D25/369

  Magnetised or magnetisable materials · CPC title

• G07D7/003

  using security elements (using digital security elements G07D7/004) · CPC title

• B42D25/373

  Metallic materials · CPC title