Optical security device and method of manufacture
US11338606B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 25, 2021 |
| Grant date | May 24, 2022 |
| Priority date | — |
| Expiry date | Feb 25, 2041 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB42D25/41
- WIPO fieldOther consumer goods
- WIPO sectorOther fields
Abstract
A security device is disclosed including a substrate and one or more focusing elements or lens structures located on one side of the substrate. The security device includes a plurality of image elements associated with each focusing element wherein the image elements include at least first and second groups of image elements. Each image element may be composed of pixels located in an object plane to be viewable through the associated focusing element. Each image element comprises a diffractive grating element or sub-wavelength grating element which when illuminated by a light source generates a diffraction image observable at a range of viewing angles around the device. Image elements of the first group are visible in a first range of viewing angles and image elements of the second group are visible in a second range of viewing angles. The security device is particularly suitable for use on security documents, such as banknotes. A method of forming a security device is also disclosed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.