Pilferage detection systems
CA 1069603 A · Owner: American District Telegraph Company · Inventors: Armstrong, Albert L.; Bakeman, Paul E. (Jr.)
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Abstract of the Disclosure In a pilferage detection system employing apparatus for generating a magnetic field of alternating polarity and predetermined fundamental frequency through which articles subject to pilferage must pass to leave a protected area and a magnetic marker associated with each article in the protected area, markers are provided which generate both odd and even harmonics of the fundamental frequency in response to the alternating magnetic field when the marker is active (i.e. a control element of the marker is magnetized) and which generate only odd harmonics of the fundamental frequency when the marker is inactive. The presence of an active marker in the alternating …
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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 January 8, 1980. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended January 8, 1997.
- 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.