Tunable liquid-crystal etalon filter
CA 2088372 C · Owner: Bell Communications Research, Inc. · Inventors: Patel, Jayantilal Shamjibhai
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A tunable liquid-crystal etalon filter comprising two dielectric stack mirrors (18, 20) defining an optical cavity into which is filled a liquid crystal (26). Electrodes (14 16) disposed on the outsides of , the mirrors apply an electric field to the liquid crystal changing its refractive index and thereby changing,its optical length. Thereby, the optical pass band of the filter can be electrically changed in a low-powered, compact, rugged and economical structure.
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 7, 1991 and granted October 5, 1999. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended August 7, 2011.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by August 7, 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
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.