Electronic automatic temperature control
CA 2076804 C · Owner: Griffith, Robert C. · Inventors: Griffith, Robert C.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A temperature control circuit is disclosed utilizing automatically either the electric heating (or cooling) element or a separate sensor to measure the instantaneous temperature of a thermal load device (40). Either a pulsating de or an ac electric power source (16) may be used with the temperature sensing occurring at near-zero points of the source voltage waveform. The sensor (68) forms one element of a Wheatstone bridge (90) which when unbalanced by a value lower than a chosen reference value, causes a monostable oscillator (70) to flip for at least several cycles of the source power. This turns on a power SCR (42) to feed electric current to the thermal load to increase its temperature …
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 August 25, 1992 and granted July 28, 1998. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended August 25, 2012.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by August 25, 2014.
- 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.