Self-diagnostic smoke detector
CA 2174175 C · Owner: Peterson, John · Inventors: Rattman, William J.; Peterson, John; Mi, Zhexin
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
The present invention provides a method for detecting whether an alarm circuit is operating outside its sensitivity range the alarm circuit having a background signal and a preset alarm threshold signal. The method involves a) increasing the background signal by a gain factor to produce a first test signal; b) comparing the first test signal against an alarm threshold signal; c) reducing the background signal by a reduction factor to produce a reduced background signal; d) increasing the reduced background signal by a gain factor to produce a second test signal; and e) comparing the second test signal against the alarm threshold signal. The alarm unit is operating outside its sensitivity …
Read the whole patent
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 April 15, 1996 and granted July 25, 2000. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended April 15, 2016.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by April 15, 2018.
- 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.