Circuit and apparatus for the optical measurement of fluid levels
CA 2064974 C · Owner: Fraser, George David · Inventors: Macdonald, Robert I.; Fraser, George David
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
An apparatus and electronic circuit for the measurement of fluid levels in containers. The circuit and apparatus constitute an instrument which measures fluid levels by optical means. Only light signals are used near the fluid itself. The instrument thus provides an intrinsically safe method of measuring fluid levels in the presence of explosive or flammable fluids vapours or, gasses, or in containers which must be electrically isolated.
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 2, 1992 and granted February 25, 1997. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended April 2, 2012.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by April 2, 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.