Electronic article surveillance tag and method for implementing same
CA 2041827 A1 · Owner: Siikarla, Risto · Inventors: Siikarla, Risto
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
In a method for enhancing the performance of tags for use in an electronic article surveillance system of the type comprising a transmitter-receiver arrangement disposed aside an area to be controlled for transmitting a first high-frequency signal into the area, a transmitter disposed aside the area and generating a second frequency signal of substantially lower frequency than the first frequency for establishing in the area an electrostatic field, a tag for attachment to an article to be subject to surveillance, the tag being responsive to the incidence thereon of energy of both the first and second frequencies to transmit a composite thereof and receiver apparatus disposed aside the area …
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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
- Filed May 3, 1991. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended May 3, 2011.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by May 3, 2013.
- 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.