Method of operating an ionization smoke alarm and ionization smoke alarm
CA 2010105 C · Owner: Beyersdorf, Hartwig · Inventors: Beyersdorf, Hartwig
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A method of the operation of an ionization smoke alarm which has a measuring chamber open to the ambient air and ionizable by a radioactive source. A measuring chamber includes a first electrode to which a supply d. c. voltage is applied and a measuring electrode the potential of which changes in response to the smoke density if smoke enters the measuring chamber. This potential is measured for producing a smoke alarm signal if it reaches a predetermined value. The potential of the measuring electrode is measured for at least one further electric field strength that is compared with at least a second potential which occurs at the second field strength according to the law of the …
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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 February 15, 1990 and granted November 12, 1996. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended February 15, 2010.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by February 15, 2012.
- 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.