Tamper evident document and use thereof
CA 1295643 C · Owner: Wallace Computer Services, Inc. · Inventors: Chang, John C.H.; Dimitriou, Theodore
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Abstract of the Disclosure, A tamper evident document comprising a support bearing an autogenous coating including chromogenic material isolated from an electron-acceptor color developer material in which the autogenous coating bears a principal image comprising visible indicia of a transfer medium imprinted on the surface of the localized autogenous coating. Tampering with the principal image causes chromogen to react with the electron-acceptor color developer material to provide a color indication of tampering. The tamper evident document can be part of a multi-ply record system comprising a plurality of sheets in superposed relationship comprising a, first sheet including a support …
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Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.
Why it's free to use
- Granted February 11, 1992. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended February 11, 2009.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
Timeline
Timeline From CIPO dates
Sources & verification
Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.