Methods, apparatus and devices relating to magnetic markers for elongated hidden objects
CA 2073769 C · Owner: Schonstedt, Erick O. · Inventors: Rippingale, John B.; Schonstedt, Erick O.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A magnetic marker serving to locate, trace and identify an elongated hidden object such as a buried utility pipe, duct, conduit, or fiber optic cable, is manufactured by applying magnetic material to a substrate (26) that is elongated and by forming from the material a helical or twisted permanent magnet pattern extending along the length of the substrate. The magnetic material which may be coextensive with the substrate (26) or applied to a portion only of the substrate may be formed as a strip (46) coex-, truded with the substrate (26) and magnetized in the direction of the width of the strip (46). Alternatively magnetic material may, be mixed with the material from which the substrate …
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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 January 30, 1991 and granted November 15, 1994. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended January 30, 2011.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by January 30, 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
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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.