Marking and authenticating documents with liquid crystal materials
Number of patents in Portfolio can not be more than 2000
United States of America Patent
Stats
-
Apr 30, 1985
Grant Date -
N/A
app pub date -
Jun 28, 1982
filing date -
Jun 28, 1982
priority date (Note) -
Expired
status (Latency Note)
Importance
Abstract
Method and apparatus for authenticating documents such as government notes and currency, stock certificates, and the like by marking the document with an encapsulated dyed liquid crystal material and examining the document for unique optical characteristics of the mark. Reading apparatus for the document measures changes in reflectivity of the liquid crystal mark with changes in an electrical field applied thereto. In other embodiments, reflectivity is measured at a plurality of different wavelengths. In one embodiment, the dye absorbs in regions of the electromagnetic spectrum 'invisible' to the human eye and the reading apparatus monitors reflectivity changes at these invisible wavelengths.
First Claim
Family
International Classification(s)
Cited Art Landscape
Patent Citation Ranking
Advertisement
Advertisement
Advertisement
Recipient Email Address
Recipient Email Address
Comment
Recipient Email Address
Add to Portfolio(s)
To add this patent to one, or more, of your portfolios, simply click the add button.
This Patent is in these Portfolios:
Add to additional portfolios:
Last Refreshed On:
Changes done successfully