Security aspects of multiexponential decays
US9448171B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 2, 2015 |
| Grant date | Sep 20, 2016 |
| Priority date | — |
| Expiry date | Jun 2, 2035 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2201/0221
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
At least two luminescent materials are intermingled within a security feature. The materials are selected from among a larger set of luminescent materials each having a different individual exponential decay characteristic (decay constant and initial amplitude response to the degree of excitation) for photo-luminescent emission from the respective material following excitation. The ratio of the decay constants for any two materials is greater than or equal to about 1.5. The selected materials are mixed in one of a plurality of predetermined ratios. The combined emissions from the intermingled materials appear, to an unsophisticated measuring device, to have a single exponential decay constant. Based on measurements for the decay of the combined emissions following excitation, estimates of the individual decay constants and associated initial emission amplitudes allow decoding of the particular combination of materials and/or their ratios to validate the security feature, authenticating the article.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.