Optically variable devices, their production and use
US9323042B2 · kind B2 · utility
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3References
35Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Apr 21, 2011 |
| Grant date | Apr 26, 2016 |
| Priority date | — |
| Expiry date | Jun 2, 2032 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB42D2035/34
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
Security documents often incorporate optically variable devices to prevent or hinder counterfeiters. Disclosed herein are layered optically variable devices such as colour-shift foils that employ a piezoelectric layer, and methods for their production and use. Such devices afford new techniques for a user of a security document to check quickly and easily whether the security document is a legitimate document or a counterfeit copy by placing an electrical potential difference across the security document.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.